diff --git a/components/ocs_algo/bit_ops.cpp b/components/ocs_algo/bit_ops.cpp
index b98e7137..d873ea28 100644
--- a/components/ocs_algo/bit_ops.cpp
+++ b/components/ocs_algo/bit_ops.cpp
@@ -8,15 +8,15 @@
 namespace ocs {
 namespace algo {
 
-unsigned BitOps::mask(uint8_t pos) {
+uint32_t BitOps::mask(uint8_t pos) {
     return (1UL << pos);
 }
 
-unsigned BitOps::umask(uint8_t pos) {
+uint32_t BitOps::umask(uint8_t pos) {
     return ~(mask(pos));
 }
 
-uint8_t BitOps::nth(unsigned value, uint8_t pos) {
+uint8_t BitOps::nth(uint32_t value, uint8_t pos) {
     return mask(pos) & value ? 1 : 0;
 }
 
diff --git a/components/ocs_algo/bit_ops.h b/components/ocs_algo/bit_ops.h
index 087ab69d..2e266bf3 100644
--- a/components/ocs_algo/bit_ops.h
+++ b/components/ocs_algo/bit_ops.h
@@ -12,13 +12,13 @@ namespace algo {
 
 struct BitOps {
     //! Create a mask with the n-th bit set.
-    static unsigned mask(uint8_t pos);
+    static uint32_t mask(uint8_t pos);
 
     //! Create a mask with the n-th bit unset.
-    static unsigned umask(uint8_t pos);
+    static uint32_t umask(uint8_t pos);
 
     //! Return the n-th bit of the value.
-    static uint8_t nth(unsigned value, uint8_t pos);
+    static uint8_t nth(uint32_t value, uint8_t pos);
 
     //! Return 16-bit value from two 8-bit values.
     static uint16_t pack_u8(uint8_t hi, uint8_t lo);
diff --git a/components/ocs_algo/container_ops.h b/components/ocs_algo/container_ops.h
index 2166ac4a..21f7a086 100644
--- a/components/ocs_algo/container_ops.h
+++ b/components/ocs_algo/container_ops.h
@@ -38,9 +38,9 @@ struct StringEqual {
 //! @notes
 //!  Based on combine hash implementation in boost:
 //!  https://www.boost.org/doc/libs/1_35_0/doc/html/boost/hash_combine_id241013.html
-template <typename T, unsigned N> struct ArrayHasher {
-    unsigned operator()(const std::array<T, N>& arr) const {
-        unsigned h = 0;
+template <typename T, size_t N> struct ArrayHasher {
+    size_t operator()(const std::array<T, N>& arr) const {
+        size_t h = 0;
 
         for (const auto& e : arr) {
             h ^= std::hash<T> {}(e) + 0x9e3779b9 + (h << 6) + (h >> 2);
diff --git a/components/ocs_algo/crc_ops.cpp b/components/ocs_algo/crc_ops.cpp
index 35412456..fbb089a2 100644
--- a/components/ocs_algo/crc_ops.cpp
+++ b/components/ocs_algo/crc_ops.cpp
@@ -9,14 +9,14 @@ namespace ocs {
 namespace algo {
 
 uint8_t CrcOps::crc8(const uint8_t* buf,
-                     unsigned size,
+                     size_t size,
                      uint8_t initial,
                      uint8_t polynomial,
                      CrcOps::BitOrder order) {
     // Initialize shift register.
     uint8_t crc = initial;
 
-    for (unsigned n = 0; n < size; ++n) {
+    for (size_t n = 0; n < size; ++n) {
         // XOR data byte with current CRC.
         crc ^= buf[n];
 
diff --git a/components/ocs_algo/crc_ops.h b/components/ocs_algo/crc_ops.h
index 37bead51..056d1897 100644
--- a/components/ocs_algo/crc_ops.h
+++ b/components/ocs_algo/crc_ops.h
@@ -5,6 +5,7 @@
 
 #pragma once
 
+#include <cstddef>
 #include <cstdint>
 
 namespace ocs {
@@ -26,7 +27,7 @@ struct CrcOps {
     //! @references
     //!  https://www.boost.org/doc/libs/1_84_0/doc/html/crc/crc_optimal.html
     static uint8_t crc8(const uint8_t* buf,
-                        unsigned size,
+                        size_t size,
                         uint8_t initial,
                         uint8_t polynomial,
                         BitOrder order);
diff --git a/components/ocs_algo/math_ops.cpp b/components/ocs_algo/math_ops.cpp
index a77d16e1..07bdd282 100644
--- a/components/ocs_algo/math_ops.cpp
+++ b/components/ocs_algo/math_ops.cpp
@@ -10,7 +10,7 @@
 namespace ocs {
 namespace algo {
 
-double MathOps::round_floor(double value, unsigned decimal_places) {
+double MathOps::round_floor(double value, uint8_t decimal_places) {
     const auto multiplier = std::pow(10.0, decimal_places);
     const auto ret = std::floor(value * multiplier) / multiplier;
     return ret;
diff --git a/components/ocs_algo/math_ops.h b/components/ocs_algo/math_ops.h
index 63035704..3e298dd6 100644
--- a/components/ocs_algo/math_ops.h
+++ b/components/ocs_algo/math_ops.h
@@ -10,7 +10,7 @@ namespace algo {
 
 struct MathOps {
     //! Round @p value down to @p decimal_places.
-    static double round_floor(double value, unsigned decimal_places);
+    static double round_floor(double value, uint8_t decimal_places);
 };
 
 } // namespace algo
diff --git a/components/ocs_algo/sha_engine_ops.h b/components/ocs_algo/sha_engine_ops.h
index 2d507d20..bed8e841 100644
--- a/components/ocs_algo/sha_engine_ops.h
+++ b/components/ocs_algo/sha_engine_ops.h
@@ -14,7 +14,7 @@ namespace algo {
 
 struct ShaEngineOps {
     //! Return the maximum number of bytes the SHA algorithm can produce on the output.
-    static constexpr unsigned hash_lenght(security::IShaEngine::Algorithm algorithm) {
+    static constexpr size_t hash_lenght(security::IShaEngine::Algorithm algorithm) {
         switch (algorithm) {
         case security::IShaEngine::Algorithm::SHA1:
             return 20;
diff --git a/components/ocs_algo/storage_ops.cpp b/components/ocs_algo/storage_ops.cpp
index 7ddd53d1..b9e58d6d 100644
--- a/components/ocs_algo/storage_ops.cpp
+++ b/components/ocs_algo/storage_ops.cpp
@@ -19,8 +19,8 @@ const char* log_tag = "storage_ops";
 status::StatusCode StorageOps::prob_read(storage::IStorage& storage,
                                          const char* key,
                                          void* buf,
-                                         unsigned size) {
-    unsigned recv_size = 0;
+                                         size_t size) {
+    size_t recv_size = 0;
     auto code = storage.probe(key, recv_size);
     if (code != status::StatusCode::OK) {
         if (code != status::StatusCode::NoData) {
diff --git a/components/ocs_algo/storage_ops.h b/components/ocs_algo/storage_ops.h
index 930c3bb8..c9d02077 100644
--- a/components/ocs_algo/storage_ops.h
+++ b/components/ocs_algo/storage_ops.h
@@ -13,7 +13,7 @@ namespace algo {
 struct StorageOps {
     //! Read string with @p key from @p storage to @p buf which can hold @p size bytes.
     static status::StatusCode
-    prob_read(storage::IStorage& storage, const char* key, void* buf, unsigned size);
+    prob_read(storage::IStorage& storage, const char* key, void* buf, size_t size);
 };
 
 } // namespace algo
diff --git a/components/ocs_algo/test/test_storage_ops.cpp b/components/ocs_algo/test/test_storage_ops.cpp
index 119bb15e..fb18e1ca 100644
--- a/components/ocs_algo/test/test_storage_ops.cpp
+++ b/components/ocs_algo/test/test_storage_ops.cpp
@@ -17,7 +17,7 @@ TEST_CASE("Storage Ops: prob read: empty storage", "[ocs_algo], [storage_ops]")
 
     test::MemoryStorage storage;
 
-    unsigned recv_value = 0;
+    size_t recv_value = 0;
 
     TEST_ASSERT_EQUAL(
         status::StatusCode::NoData,
@@ -29,17 +29,17 @@ TEST_CASE("Storage Ops: prob read: empty storage", "[ocs_algo], [storage_ops]")
 TEST_CASE("Storage Ops: prob read: invalid key", "[ocs_algo], [storage_ops]") {
     const char* key = "foo";
     const char* invalid_key = "bar";
-    const unsigned value = 42;
+    const size_t value = 42;
 
     test::MemoryStorage storage;
 
     TEST_ASSERT_EQUAL(status::StatusCode::OK, storage.write(key, &value, sizeof(value)));
 
-    unsigned size = 0;
+    size_t size = 0;
     TEST_ASSERT_EQUAL(status::StatusCode::OK, storage.probe(key, size));
     TEST_ASSERT_EQUAL(size, sizeof(value));
 
-    unsigned recv_value = 0;
+    size_t recv_value = 0;
 
     TEST_ASSERT_EQUAL(
         status::StatusCode::NoData,
@@ -50,13 +50,13 @@ TEST_CASE("Storage Ops: prob read: invalid key", "[ocs_algo], [storage_ops]") {
 
 TEST_CASE("Storage Ops: prob read: size mismatch", "[ocs_algo], [storage_ops]") {
     const char* key = "foo";
-    const unsigned value = 42;
+    const size_t value = 42;
 
     test::MemoryStorage storage;
 
     TEST_ASSERT_EQUAL(status::StatusCode::OK, storage.write(key, &value, sizeof(value)));
 
-    unsigned recv_value = 0;
+    size_t recv_value = 0;
 
     TEST_ASSERT_EQUAL(
         status::StatusCode::InvalidArg,
@@ -67,7 +67,7 @@ TEST_CASE("Storage Ops: prob read: size mismatch", "[ocs_algo], [storage_ops]")
 
 TEST_CASE("Storage Ops: prob read: prob failed", "[ocs_algo], [storage_ops]") {
     const char* key = "foo";
-    const unsigned value = 42;
+    const size_t value = 42;
 
     test::MemoryStorage memory_storage;
     test::StatusStorage storage(memory_storage);
@@ -75,7 +75,7 @@ TEST_CASE("Storage Ops: prob read: prob failed", "[ocs_algo], [storage_ops]") {
 
     TEST_ASSERT_EQUAL(status::StatusCode::OK, storage.write(key, &value, sizeof(value)));
 
-    unsigned recv_value = 0;
+    size_t recv_value = 0;
 
     TEST_ASSERT_EQUAL(
         storage.probe_status,
@@ -86,7 +86,7 @@ TEST_CASE("Storage Ops: prob read: prob failed", "[ocs_algo], [storage_ops]") {
 
 TEST_CASE("Storage Ops: prob read: read failed", "[ocs_algo], [storage_ops]") {
     const char* key = "foo";
-    const unsigned value = 42;
+    const size_t value = 42;
 
     test::MemoryStorage memory_storage;
     test::StatusStorage storage(memory_storage);
@@ -94,7 +94,7 @@ TEST_CASE("Storage Ops: prob read: read failed", "[ocs_algo], [storage_ops]") {
 
     TEST_ASSERT_EQUAL(status::StatusCode::OK, storage.write(key, &value, sizeof(value)));
 
-    unsigned recv_value = 0;
+    size_t recv_value = 0;
 
     TEST_ASSERT_EQUAL(
         storage.read_status,
@@ -105,13 +105,13 @@ TEST_CASE("Storage Ops: prob read: read failed", "[ocs_algo], [storage_ops]") {
 
 TEST_CASE("Storage Ops: prob read: properly read", "[ocs_algo], [storage_ops]") {
     const char* key = "foo";
-    const unsigned value = 42;
+    const size_t value = 42;
 
     test::MemoryStorage storage;
 
     TEST_ASSERT_EQUAL(status::StatusCode::OK, storage.write(key, &value, sizeof(value)));
 
-    unsigned recv_value = 0;
+    size_t recv_value = 0;
 
     TEST_ASSERT_EQUAL(
         status::StatusCode::OK,
diff --git a/components/ocs_algo/uri_ops.cpp b/components/ocs_algo/uri_ops.cpp
index 67c409a0..08de2e7a 100644
--- a/components/ocs_algo/uri_ops.cpp
+++ b/components/ocs_algo/uri_ops.cpp
@@ -36,7 +36,7 @@ UriOps::Path UriOps::parse_path(const char* uri) {
         return std::string_view();
     }
 
-    unsigned path_length = 0;
+    size_t path_length = 0;
 
     const char* query_start = strchr(uri, '?');
     if (query_start != nullptr) {
diff --git a/components/ocs_control/flip_led_task.cpp b/components/ocs_control/flip_led_task.cpp
index 48c3e749..52b1aa77 100644
--- a/components/ocs_control/flip_led_task.cpp
+++ b/components/ocs_control/flip_led_task.cpp
@@ -14,7 +14,7 @@ namespace control {
 FlipLedTask::FlipLedTask(scheduler::IEventHandler& handler,
                          ILed& led,
                          ILed::Priority priority,
-                         unsigned flip_count)
+                         size_t flip_count)
     : priority_(priority)
     , flip_count_(flip_count)
     , handler_(handler)
diff --git a/components/ocs_control/flip_led_task.h b/components/ocs_control/flip_led_task.h
index a62caedc..304d0cff 100644
--- a/components/ocs_control/flip_led_task.h
+++ b/components/ocs_control/flip_led_task.h
@@ -25,7 +25,7 @@ class FlipLedTask : public scheduler::ITask, private core::NonCopyable<> {
     FlipLedTask(scheduler::IEventHandler& handler,
                 ILed& led,
                 ILed::Priority priority,
-                unsigned flip_count);
+                size_t flip_count);
 
     //! Flip LED on each task run.
     //!
@@ -40,7 +40,7 @@ class FlipLedTask : public scheduler::ITask, private core::NonCopyable<> {
 private:
     const ILed::Priority priority_ { ILed::Priority::None };
 
-    unsigned flip_count_ { 0 };
+    size_t flip_count_ { 0 };
 
     scheduler::IEventHandler& handler_;
     ILed& led_;
diff --git a/components/ocs_control/system_fsm.cpp b/components/ocs_control/system_fsm.cpp
index 20156572..c9f0522a 100644
--- a/components/ocs_control/system_fsm.cpp
+++ b/components/ocs_control/system_fsm.cpp
@@ -245,7 +245,7 @@ void SystemFsm::add_fsr_task_() {
                  == status::StatusCode::OK);
 }
 
-void SystemFsm::add_led_task_(unsigned flip_count) {
+void SystemFsm::add_led_task_(size_t flip_count) {
     configASSERT(!task_);
 
     task_.reset(new (std::nothrow)
diff --git a/components/ocs_control/system_fsm.h b/components/ocs_control/system_fsm.h
index 14ac4b2c..c0caad1a 100644
--- a/components/ocs_control/system_fsm.h
+++ b/components/ocs_control/system_fsm.h
@@ -91,14 +91,14 @@ class SystemFsm : public IButtonHandler,
     void handle_state_fsr_done_();
 
     void add_fsr_task_();
-    void add_led_task_(unsigned flip_count);
+    void add_led_task_(size_t flip_count);
     void remove_task_();
 
     bool button_was_pressed_();
 
     static constexpr system::Time task_interval_ = system::Duration::second / 2;
-    static constexpr unsigned flip_count_init_ = 6;
-    static constexpr unsigned flip_count_button_pressed_ = 2;
+    static constexpr uint8_t flip_count_init_ = 6;
+    static constexpr uint8_t flip_count_button_pressed_ = 2;
     static constexpr const char* task_id_ = "sys_fsm_led";
 
     const Params params_;
diff --git a/components/ocs_control/test/test_button_event_handler.cpp b/components/ocs_control/test/test_button_event_handler.cpp
index 5f6d92df..aa2ecc51 100644
--- a/components/ocs_control/test/test_button_event_handler.cpp
+++ b/components/ocs_control/test/test_button_event_handler.cpp
@@ -23,7 +23,7 @@ struct TestButton : public IButton, private core::NonCopyable<> {
 
 struct TestButtonHandler : public IButtonHandler, private core::NonCopyable<> {
     system::Time pressed_duration { 0 };
-    unsigned pressed_call_count { 0 };
+    size_t pressed_call_count { 0 };
 
     status::StatusCode handle_pressed(system::Time duration) {
         pressed_duration = duration;
diff --git a/components/ocs_control/test/test_fsm_block.cpp b/components/ocs_control/test/test_fsm_block.cpp
index 6b6f2572..8e21f4fb 100644
--- a/components/ocs_control/test/test_fsm_block.cpp
+++ b/components/ocs_control/test/test_fsm_block.cpp
@@ -97,7 +97,7 @@ TEST_CASE("FSM block: transit: save state", "[ocs_control], [fsm_block]") {
     const system::Time resolution = system::Duration::second;
     const char* id = "block_id";
     uint64_t write_count = 17;
-    const unsigned state_duration = 42;
+    const size_t state_duration = 42;
 
     TestFsmBlockStorage storage;
     storage.write_count = write_count;
@@ -141,7 +141,7 @@ TEST_CASE("FSM block: transit: failed to save state", "[ocs_control], [fsm_block
     const system::Time resolution = system::Duration::second;
     const char* id = "block_id";
     const uint64_t write_count = 17;
-    const unsigned state_duration = 42;
+    const size_t state_duration = 42;
 
     TestFsmBlockStorage storage;
     storage.write_count = write_count;
diff --git a/components/ocs_control/test/test_fsm_block_storage.cpp b/components/ocs_control/test/test_fsm_block_storage.cpp
index ae513a07..d80e1142 100644
--- a/components/ocs_control/test/test_fsm_block_storage.cpp
+++ b/components/ocs_control/test/test_fsm_block_storage.cpp
@@ -21,11 +21,11 @@ TestFsmBlockStorage::TestFsmBlockStorage(status::StatusCode read_status,
     , erase_status(erase_status) {
 }
 
-status::StatusCode TestFsmBlockStorage::probe(const char* key, unsigned& size) {
+status::StatusCode TestFsmBlockStorage::probe(const char* key, size_t& size) {
     return status::StatusCode::Error;
 }
 
-status::StatusCode TestFsmBlockStorage::read(const char* key, void* data, unsigned size) {
+status::StatusCode TestFsmBlockStorage::read(const char* key, void* data, size_t size) {
     if (read_status != status::StatusCode::OK) {
         return read_status;
     }
@@ -53,7 +53,7 @@ status::StatusCode TestFsmBlockStorage::read(const char* key, void* data, unsign
 }
 
 status::StatusCode
-TestFsmBlockStorage::write(const char* key, const void* data, unsigned size) {
+TestFsmBlockStorage::write(const char* key, const void* data, size_t size) {
     if (write_status != status::StatusCode::OK) {
         return write_status;
     }
diff --git a/components/ocs_control/test/test_fsm_store.cpp b/components/ocs_control/test/test_fsm_store.cpp
index 226ecd74..1a31b61b 100644
--- a/components/ocs_control/test/test_fsm_store.cpp
+++ b/components/ocs_control/test/test_fsm_store.cpp
@@ -51,8 +51,8 @@ class TestHandler : public IFsmHandler, private core::NonCopyable<> {
         return status::StatusCode::OK;
     }
 
-    unsigned handle_state_count { 0 };
-    unsigned handle_transit_count { 0 };
+    size_t handle_state_count { 0 };
+    size_t handle_transit_count { 0 };
 
     status::StatusCode state_result { status::StatusCode::OK };
     status::StatusCode transit_result { status::StatusCode::OK };
diff --git a/components/ocs_control/test/test_led_locator.cpp b/components/ocs_control/test/test_led_locator.cpp
index 4f774b6e..6793135a 100644
--- a/components/ocs_control/test/test_led_locator.cpp
+++ b/components/ocs_control/test/test_led_locator.cpp
@@ -28,7 +28,7 @@ class AsyncTestRunner : private core::NonCopyable<> {
 public:
     AsyncTestRunner(scheduler::ITaskScheduler& task_scheduler,
                     const char* id,
-                    unsigned stack_size)
+                    size_t stack_size)
         : id_(id)
         , stack_size_(stack_size)
         , task_scheduler_(task_scheduler) {
@@ -69,7 +69,7 @@ class AsyncTestRunner : private core::NonCopyable<> {
     }
 
     const std::string id_;
-    const unsigned stack_size_ { 0 };
+    const size_t stack_size_ { 0 };
 
     scheduler::ITaskScheduler& task_scheduler_;
 
@@ -104,7 +104,7 @@ TEST_CASE("LED locator: turn-on/turn-off/flip", "[ocs_control], [led_locator]")
     TEST_ASSERT_TRUE(locator.get());
 
     auto get_flip_count = [](test::TestGpio& gpio, scheduler::AsyncFuncScheduler& ash) {
-        unsigned ret = 0;
+        size_t ret = 0;
 
         auto future = ash.add([&gpio, &ret]() {
             ret = gpio.flip_call_count;
@@ -119,7 +119,7 @@ TEST_CASE("LED locator: turn-on/turn-off/flip", "[ocs_control], [led_locator]")
         return ret;
     };
 
-    unsigned last_flip_count = 0;
+    size_t last_flip_count = 0;
 
     while (true) {
         if (get_flip_count(gpio, func_scheduler) > last_flip_count + 5) {
@@ -134,7 +134,7 @@ TEST_CASE("LED locator: turn-on/turn-off/flip", "[ocs_control], [led_locator]")
 
     last_flip_count = get_flip_count(gpio, func_scheduler);
 
-    for (unsigned n = 0; n < 10; ++n) {
+    for (size_t n = 0; n < 10; ++n) {
         TEST_ASSERT_EQUAL(last_flip_count, get_flip_count(gpio, func_scheduler));
         vTaskDelay(pdMS_TO_TICKS(50));
     }
@@ -155,7 +155,7 @@ TEST_CASE("LED locator: turn-on/turn-off/flip", "[ocs_control], [led_locator]")
 
     last_flip_count = get_flip_count(gpio, func_scheduler);
 
-    for (unsigned n = 0; n < 10; ++n) {
+    for (size_t n = 0; n < 10; ++n) {
         TEST_ASSERT_EQUAL(last_flip_count, get_flip_count(gpio, func_scheduler));
         vTaskDelay(pdMS_TO_TICKS(50));
     }
@@ -180,7 +180,7 @@ TEST_CASE("LED locator: turn-on/turn-off/flip", "[ocs_control], [led_locator]")
 
     last_flip_count = get_flip_count(gpio, func_scheduler);
 
-    for (unsigned n = 0; n < 10; ++n) {
+    for (size_t n = 0; n < 10; ++n) {
         TEST_ASSERT_EQUAL(last_flip_count, get_flip_count(gpio, func_scheduler));
         vTaskDelay(pdMS_TO_TICKS(50));
     }
@@ -213,7 +213,7 @@ TEST_CASE("LED locator: disable locating when the LED is locked by another compo
     TEST_ASSERT_TRUE(locator.get());
 
     auto get_flip_count = [](test::TestGpio& gpio, scheduler::AsyncFuncScheduler& ash) {
-        unsigned ret = 0;
+        size_t ret = 0;
 
         auto future = ash.add([&gpio, &ret]() {
             ret = gpio.flip_call_count;
@@ -228,7 +228,7 @@ TEST_CASE("LED locator: disable locating when the LED is locked by another compo
         return ret;
     };
 
-    unsigned last_flip_count = 0;
+    size_t last_flip_count = 0;
 
     while (true) {
         if (get_flip_count(gpio, func_scheduler) > last_flip_count + 5) {
@@ -256,7 +256,7 @@ TEST_CASE("LED locator: disable locating when the LED is locked by another compo
 
     last_flip_count = get_flip_count(gpio, func_scheduler);
 
-    for (unsigned n = 0; n < 10; ++n) {
+    for (size_t n = 0; n < 10; ++n) {
         TEST_ASSERT_EQUAL(last_flip_count, get_flip_count(gpio, func_scheduler));
         vTaskDelay(pdMS_TO_TICKS(50));
     }
diff --git a/components/ocs_control/test/test_system_fsm.cpp b/components/ocs_control/test/test_system_fsm.cpp
index dafea08e..a3e40268 100644
--- a/components/ocs_control/test/test_system_fsm.cpp
+++ b/components/ocs_control/test/test_system_fsm.cpp
@@ -19,7 +19,7 @@ namespace control {
 namespace {
 
 struct TestRebooter : public system::IRebooter, private core::NonCopyable<> {
-    unsigned call_count { 0 };
+    size_t call_count { 0 };
 
     void reboot() override {
         ++call_count;
@@ -35,7 +35,7 @@ struct TestButton : public IButton, private core::NonCopyable<> {
 };
 
 struct TestFsrHandler : public IFsrHandler, private core::NonCopyable<> {
-    unsigned call_count { 0 };
+    size_t call_count { 0 };
 
     status::StatusCode handle_fsr() override {
         ++call_count;
@@ -45,7 +45,7 @@ struct TestFsrHandler : public IFsrHandler, private core::NonCopyable<> {
 };
 
 struct TestInitHandler : public scheduler::IEventHandler, private core::NonCopyable<> {
-    unsigned call_count { 0 };
+    size_t call_count { 0 };
 
     status::StatusCode handle_event() override {
         ++call_count;
@@ -91,7 +91,7 @@ TEST_CASE("System FSM: button is pressed before LED reaction on system initializ
     TEST_ASSERT_EQUAL(status::StatusCode::OK, fsm.run());
 
     // Ensure there is no LED reaction on button event.
-    for (unsigned n = 0; n < 10; ++n) {
+    for (size_t n = 0; n < 10; ++n) {
         TEST_ASSERT_EQUAL(status::StatusCode::OK, task_scheduler.run());
         TEST_ASSERT_EQUAL(0, gpio.flip_call_count);
     }
@@ -184,7 +184,7 @@ TEST_CASE("System FSM: button is pressed during LED reaction on system initializ
     TEST_ASSERT_EQUAL(status::StatusCode::OK, fsm.run());
 
     // Ensure there is no LED reaction on button event.
-    for (unsigned n = 0; n < 10; ++n) {
+    for (size_t n = 0; n < 10; ++n) {
         TEST_ASSERT_EQUAL(status::StatusCode::OK, task_scheduler.run());
         TEST_ASSERT_EQUAL(0, gpio.flip_call_count);
     }
@@ -232,7 +232,7 @@ TEST_CASE("System FSM: button isn't released within interval",
     TEST_ASSERT_EQUAL(status::StatusCode::OK, fsm.run());
 
     // Ensure there is no LED reaction on button event.
-    for (unsigned n = 0; n < 10; ++n) {
+    for (size_t n = 0; n < 10; ++n) {
         TEST_ASSERT_EQUAL(status::StatusCode::OK, task_scheduler.run());
         TEST_ASSERT_EQUAL(0, gpio.flip_call_count);
     }
@@ -373,7 +373,7 @@ TEST_CASE("System FSM: FSR canceled: released too quickly",
     TEST_ASSERT_EQUAL(0, fsr_handler.call_count);
 
     // Ensure there is no LED reaction on button event.
-    for (unsigned n = 0; n < 10; ++n) {
+    for (size_t n = 0; n < 10; ++n) {
         TEST_ASSERT_EQUAL(status::StatusCode::OK, task_scheduler.run());
         TEST_ASSERT_EQUAL(0, gpio.flip_call_count);
     }
@@ -454,7 +454,7 @@ TEST_CASE("System FSM: FSR canceled: isn't confirmed within timeout",
     TEST_ASSERT_EQUAL(0, fsr_handler.call_count);
 
     // Ensure there is no LED reaction on button event.
-    for (unsigned n = 0; n < 10; ++n) {
+    for (size_t n = 0; n < 10; ++n) {
         TEST_ASSERT_EQUAL(status::StatusCode::OK, task_scheduler.run());
         TEST_ASSERT_EQUAL(0, gpio.flip_call_count);
     }
diff --git a/components/ocs_core/file_stream_reader.cpp b/components/ocs_core/file_stream_reader.cpp
index 134328f1..66ef8179 100644
--- a/components/ocs_core/file_stream_reader.cpp
+++ b/components/ocs_core/file_stream_reader.cpp
@@ -71,7 +71,7 @@ status::StatusCode FileStreamReader::cancel() {
     return ret ? status::StatusCode::Error : status::StatusCode::OK;
 }
 
-status::StatusCode FileStreamReader::read(void* data, unsigned& size) {
+status::StatusCode FileStreamReader::read(void* data, size_t& size) {
     configASSERT(file_);
 
     if (feof(file_)) {
diff --git a/components/ocs_core/file_stream_reader.h b/components/ocs_core/file_stream_reader.h
index dc5fef93..4397910b 100644
--- a/components/ocs_core/file_stream_reader.h
+++ b/components/ocs_core/file_stream_reader.h
@@ -39,7 +39,7 @@ class FileStreamReader : public IStreamReader, private core::NonCopyable<> {
     status::StatusCode cancel() override;
 
     //! Read up to @p size bytes from file to @p data.
-    status::StatusCode read(void* data, unsigned& size) override;
+    status::StatusCode read(void* data, size_t& size) override;
 
 private:
     const std::string path_;
diff --git a/components/ocs_core/istream_reader.h b/components/ocs_core/istream_reader.h
index 02f6111d..59332a17 100644
--- a/components/ocs_core/istream_reader.h
+++ b/components/ocs_core/istream_reader.h
@@ -13,7 +13,7 @@ namespace core {
 //! Stream reading process.
 //!
 //! @example
-//!  status::StatusCode read_data(IStreamReader& reader, void* data, unsigned size) {
+//!  status::StatusCode read_data(IStreamReader& reader, void* data, size_t size) {
 //!     if (const auto code = reader.begin(); code != status::StatusCode::OK) {
 //!         return code;
 //!     }
@@ -64,7 +64,7 @@ class IStreamReader {
     //!
     //! @notes
     //!  Reading is only allowed after the process was started correctly via begin() call.
-    virtual status::StatusCode read(void* data, unsigned& size) = 0;
+    virtual status::StatusCode read(void* data, size_t& size) = 0;
 };
 
 } // namespace core
diff --git a/components/ocs_core/istream_writer.h b/components/ocs_core/istream_writer.h
index 63b53644..8b52f6e7 100644
--- a/components/ocs_core/istream_writer.h
+++ b/components/ocs_core/istream_writer.h
@@ -13,7 +13,7 @@ namespace core {
 //! Stream writing process.
 //!
 //! @example
-//!  status::StatusCode write(IStreamWriter& writer, const void* data, unsigned size) {
+//!  status::StatusCode write(IStreamWriter& writer, const void* data, size_t size) {
 //!     if (const auto code = writer.begin(); code != status::StatusCode::OK) {
 //!         return code;
 //!     }
@@ -57,7 +57,7 @@ class IStreamWriter {
     //!
     //! @notes
     //!  Writing is only allowed after the process was started correctly via begin() call.
-    virtual status::StatusCode write(const void* data, unsigned size) = 0;
+    virtual status::StatusCode write(const void* data, size_t size) = 0;
 };
 
 } // namespace core
diff --git a/components/ocs_core/stream_transceiver.cpp b/components/ocs_core/stream_transceiver.cpp
index 58c692e5..fba8fc2f 100644
--- a/components/ocs_core/stream_transceiver.cpp
+++ b/components/ocs_core/stream_transceiver.cpp
@@ -50,7 +50,7 @@ status::StatusCode StreamTransceiver::transceive() {
     while (true) {
         buffer_.clear();
 
-        unsigned size = buffer_.capacity();
+        size_t size = buffer_.capacity();
 
         auto code = reader_.read(buffer_.data(), size);
         if (code == status::StatusCode::OK) {
diff --git a/components/ocs_core/test/test_cond.cpp b/components/ocs_core/test/test_cond.cpp
index 8a5ffc00..eb225553 100644
--- a/components/ocs_core/test/test_cond.cpp
+++ b/components/ocs_core/test/test_cond.cpp
@@ -34,7 +34,7 @@ template <typename T> T random(T range_from, T range_to) {
 
 class TestTask : private NonCopyable<> {
 public:
-    TestTask(ILocker& locker, Cond& cond, const char* id, unsigned stack_size)
+    TestTask(ILocker& locker, Cond& cond, const char* id, size_t stack_size)
         : id_(id)
         , stack_size_(stack_size)
         , locker_(locker)
@@ -48,7 +48,7 @@ class TestTask : private NonCopyable<> {
         return ret == pdTRUE ? status::StatusCode::OK : status::StatusCode::Error;
     }
 
-    unsigned awake_count() const {
+    size_t awake_count() const {
         return awake_count_.load(std::memory_order_acquire);
     }
 
@@ -76,13 +76,13 @@ class TestTask : private NonCopyable<> {
     }
 
     const std::string id_;
-    const unsigned stack_size_ { 0 };
+    const size_t stack_size_ { 0 };
 
     ILocker& locker_;
     Cond& cond_;
 
     TaskHandle_t handle_ { nullptr };
-    std::atomic<unsigned> awake_count_ { 0 };
+    std::atomic<size_t> awake_count_ { 0 };
 };
 
 } // namespace
@@ -91,13 +91,13 @@ TEST_CASE("Condition variable: wait multiple tasks", "[ocs_core], [cond]") {
     StaticMutex mutex;
     Cond cond(mutex);
 
-    const unsigned task_count = 3;
-    const unsigned stack_size = 1024 * 2;
+    const size_t task_count = 3;
+    const size_t stack_size = 1024 * 2;
 
     using TaskPtr = std::shared_ptr<TestTask>;
     std::vector<TaskPtr> tasks;
 
-    for (unsigned n = 0; n < task_count; ++n) {
+    for (size_t n = 0; n < task_count; ++n) {
         const std::string id = "task_" + std::to_string(n);
 
         TaskPtr task(new (std::nothrow) TestTask(mutex, cond, id.c_str(), stack_size));
diff --git a/components/ocs_core/test/test_stream_transceiver.cpp b/components/ocs_core/test/test_stream_transceiver.cpp
index f2c8ddca..24b23ca8 100644
--- a/components/ocs_core/test/test_stream_transceiver.cpp
+++ b/components/ocs_core/test/test_stream_transceiver.cpp
@@ -41,7 +41,7 @@ struct TestStreamReader : public IStreamReader {
         return cancel_status;
     }
 
-    status::StatusCode read(void* data, unsigned& size) override {
+    status::StatusCode read(void* data, size_t& size) override {
         ++read_count;
 
         if (read_status != status::StatusCode::OK) {
@@ -65,10 +65,10 @@ struct TestStreamReader : public IStreamReader {
     status::StatusCode cancel_status { status::StatusCode::OK };
     status::StatusCode read_status { status::StatusCode::OK };
 
-    unsigned begin_count { 0 };
-    unsigned end_count { 0 };
-    unsigned cancel_count { 0 };
-    unsigned read_count { 0 };
+    size_t begin_count { 0 };
+    size_t end_count { 0 };
+    size_t cancel_count { 0 };
+    size_t read_count { 0 };
 
 private:
     Data data_;
@@ -90,7 +90,7 @@ struct TestStreamWriter : public IStreamWriter {
         return cancel_status;
     }
 
-    status::StatusCode write(const void* data, unsigned size) override {
+    status::StatusCode write(const void* data, size_t size) override {
         ++write_count;
         if (write_status != status::StatusCode::OK) {
             return write_status;
@@ -98,7 +98,7 @@ struct TestStreamWriter : public IStreamWriter {
 
         const char* ptr = static_cast<const char*>(data);
 
-        for (unsigned n = 0; n < size; ++n) {
+        for (size_t n = 0; n < size; ++n) {
             buffer_.push_back(ptr[n]);
         }
 
@@ -114,10 +114,10 @@ struct TestStreamWriter : public IStreamWriter {
     status::StatusCode cancel_status { status::StatusCode::OK };
     status::StatusCode write_status { status::StatusCode::OK };
 
-    unsigned begin_count { 0 };
-    unsigned end_count { 0 };
-    unsigned cancel_count { 0 };
-    unsigned write_count { 0 };
+    size_t begin_count { 0 };
+    size_t end_count { 0 };
+    size_t cancel_count { 0 };
+    size_t write_count { 0 };
 
 private:
     StreamTransceiver::Buffer buffer_;
diff --git a/components/ocs_core/version_to_str.cpp b/components/ocs_core/version_to_str.cpp
index 2814ae24..181b9e2b 100644
--- a/components/ocs_core/version_to_str.cpp
+++ b/components/ocs_core/version_to_str.cpp
@@ -13,9 +13,8 @@ namespace core {
 version_to_str::version_to_str(Version version) {
     memset(buf_, 0, sizeof(buf_));
 
-    if (snprintf(buf_, sizeof(buf_), "%u.%u.%u", static_cast<unsigned>(version.major),
-                 static_cast<unsigned>(version.minor),
-                 static_cast<unsigned>(version.patch))
+    if (snprintf(buf_, sizeof(buf_), "%u.%u.%u", static_cast<size_t>(version.major),
+                 static_cast<size_t>(version.minor), static_cast<size_t>(version.patch))
         < 0) {
         strcpy(buf_, "<none>");
     }
diff --git a/components/ocs_core/version_to_str.h b/components/ocs_core/version_to_str.h
index 9b3a1e64..5db33458 100644
--- a/components/ocs_core/version_to_str.h
+++ b/components/ocs_core/version_to_str.h
@@ -22,7 +22,7 @@ class version_to_str : private NonCopyable<> {
     const char* c_str() const;
 
 private:
-    static constexpr unsigned size_ = strlen("65535.65535.65535");
+    static constexpr size_t size_ = strlen("65535.65535.65535");
 
     char buf_[size_ + 1];
 };
diff --git a/components/ocs_diagnostic/basic_counter.cpp b/components/ocs_diagnostic/basic_counter.cpp
index 8355e7c2..865d8394 100644
--- a/components/ocs_diagnostic/basic_counter.cpp
+++ b/components/ocs_diagnostic/basic_counter.cpp
@@ -18,7 +18,7 @@ BasicCounter::BasicCounter(const char* id) {
     configASSERT(strlen(id));
 
     memset(buf_, 0, sizeof(buf_));
-    strncpy(buf_, id, std::min(bufsize_, strlen(id)));
+    strncpy(buf_, id, std::min(static_cast<size_t>(bufsize_), strlen(id)));
 }
 
 const char* BasicCounter::id() const {
diff --git a/components/ocs_diagnostic/basic_counter.h b/components/ocs_diagnostic/basic_counter.h
index 2f9406c6..fbf28cb7 100644
--- a/components/ocs_diagnostic/basic_counter.h
+++ b/components/ocs_diagnostic/basic_counter.h
@@ -26,7 +26,7 @@ class BasicCounter : public ICounter, public core::NonCopyable<BasicCounter> {
     const char* id() const;
 
 private:
-    static constexpr unsigned bufsize_ = 15;
+    static constexpr uint8_t bufsize_ = 15;
 
     char buf_[bufsize_ + 1];
 };
diff --git a/components/ocs_diagnostic/test/test_basic_counter.cpp b/components/ocs_diagnostic/test/test_basic_counter.cpp
index 56419510..fc01ead7 100644
--- a/components/ocs_diagnostic/test/test_basic_counter.cpp
+++ b/components/ocs_diagnostic/test/test_basic_counter.cpp
@@ -22,12 +22,12 @@ TEST_CASE("Basic counter: ID length overflow", "[ocs_diagnostic], [basic_counter
     const auto max_len = 15;
 
     std::string actual_id;
-    for (unsigned n = 0; n < max_len * 2; ++n) {
+    for (size_t n = 0; n < max_len * 2; ++n) {
         actual_id += std::to_string(1);
     }
 
     std::string expected_id;
-    for (unsigned n = 0; n < max_len; ++n) {
+    for (size_t n = 0; n < max_len; ++n) {
         expected_id += std::to_string(1);
     }
 
diff --git a/components/ocs_fmt/json/dynamic_formatter.cpp b/components/ocs_fmt/json/dynamic_formatter.cpp
index 1a060a5f..166eb18b 100644
--- a/components/ocs_fmt/json/dynamic_formatter.cpp
+++ b/components/ocs_fmt/json/dynamic_formatter.cpp
@@ -13,7 +13,7 @@ namespace ocs {
 namespace fmt {
 namespace json {
 
-DynamicFormatter::DynamicFormatter(unsigned size)
+DynamicFormatter::DynamicFormatter(size_t size)
     : size_(size) {
     configASSERT(size_);
 
diff --git a/components/ocs_fmt/json/dynamic_formatter.h b/components/ocs_fmt/json/dynamic_formatter.h
index a1833734..21af36f4 100644
--- a/components/ocs_fmt/json/dynamic_formatter.h
+++ b/components/ocs_fmt/json/dynamic_formatter.h
@@ -20,7 +20,7 @@ class DynamicFormatter : public IFormatter, private core::NonCopyable<> {
     //!
     //! @params
     //!  - @p size - underlying buffer size, in bytes, allocated on the heap.
-    explicit DynamicFormatter(unsigned size);
+    explicit DynamicFormatter(size_t size);
 
     //! Format @p json into the underlying buffer.
     status::StatusCode format(cJSON* json) override;
@@ -31,7 +31,7 @@ class DynamicFormatter : public IFormatter, private core::NonCopyable<> {
 private:
     void clear_();
 
-    const unsigned size_ { 0 };
+    const size_t size_ { 0 };
 
     std::unique_ptr<char[]> buf_;
 };
diff --git a/components/ocs_fmt/json/static_formatter.h b/components/ocs_fmt/json/static_formatter.h
index c884db8f..3e10d52b 100644
--- a/components/ocs_fmt/json/static_formatter.h
+++ b/components/ocs_fmt/json/static_formatter.h
@@ -15,7 +15,7 @@ namespace ocs {
 namespace fmt {
 namespace json {
 
-template <unsigned Size>
+template <size_t Size>
 class StaticFormatter : public IFormatter, private core::NonCopyable<> {
 public:
     //! Initialize.
diff --git a/components/ocs_http/chunk_stream_writer.cpp b/components/ocs_http/chunk_stream_writer.cpp
index 94475535..b1ff289e 100644
--- a/components/ocs_http/chunk_stream_writer.cpp
+++ b/components/ocs_http/chunk_stream_writer.cpp
@@ -24,7 +24,7 @@ status::StatusCode ChunkStreamWriter::cancel() {
     return end();
 }
 
-status::StatusCode ChunkStreamWriter::write(const void* data, unsigned size) {
+status::StatusCode ChunkStreamWriter::write(const void* data, size_t size) {
     return writer_.write(data, size);
 }
 
diff --git a/components/ocs_http/chunk_stream_writer.h b/components/ocs_http/chunk_stream_writer.h
index 015febd2..1e70f820 100644
--- a/components/ocs_http/chunk_stream_writer.h
+++ b/components/ocs_http/chunk_stream_writer.h
@@ -5,6 +5,8 @@
 
 #pragma once
 
+#include <cstddef>
+
 #include "ocs_core/istream_writer.h"
 #include "ocs_core/noncopyable.h"
 #include "ocs_http/iresponse_writer.h"
@@ -31,7 +33,7 @@ class ChunkStreamWriter : public core::IStreamWriter, private core::NonCopyable<
     status::StatusCode cancel() override;
 
     //! Write @p size bytes of @p data.
-    status::StatusCode write(const void* data, unsigned size) override;
+    status::StatusCode write(const void* data, size_t size) override;
 
 private:
     IResponseWriter& writer_;
diff --git a/components/ocs_http/iresponse_writer.h b/components/ocs_http/iresponse_writer.h
index 34e5ef63..b611cdc0 100644
--- a/components/ocs_http/iresponse_writer.h
+++ b/components/ocs_http/iresponse_writer.h
@@ -21,7 +21,7 @@ class IResponseWriter {
     //!
     //! @remarks
     //!  - Respond with empty data to signal HTTP response completion: write(nullptr, 0).
-    virtual status::StatusCode write(const void* data, unsigned size) = 0;
+    virtual status::StatusCode write(const void* data, size_t size) = 0;
 
     //! Write HTTP status code.
     virtual status::StatusCode write_status(StatusCode) = 0;
diff --git a/components/ocs_http/target_esp32/client_reader.cpp b/components/ocs_http/target_esp32/client_reader.cpp
index 64d017c1..0a5d4dfd 100644
--- a/components/ocs_http/target_esp32/client_reader.cpp
+++ b/components/ocs_http/target_esp32/client_reader.cpp
@@ -46,10 +46,10 @@ status::StatusCode ClientReader::wait(TickType_t wait) {
     return status::StatusCode::OK;
 }
 
-unsigned ClientReader::read(char* buf, unsigned size) {
+size_t ClientReader::read(char* buf, size_t size) {
     core::LockGuard lock(mu_);
 
-    const unsigned len = std::min(size, buf_.size());
+    const size_t len = std::min(size, buf_.size());
     memcpy(buf, buf_.data(), len);
 
     return len;
@@ -104,7 +104,7 @@ void ClientReader::handle_event_on_data_(esp_http_client_event_t* event) {
 
     const char* ptr = static_cast<const char*>(event->data);
 
-    for (unsigned n = 0; n < event->data_len; ++n) {
+    for (size_t n = 0; n < event->data_len; ++n) {
         buf_.push_back(ptr[n]);
     }
 }
diff --git a/components/ocs_http/target_esp32/client_reader.h b/components/ocs_http/target_esp32/client_reader.h
index 94a947b6..5758ab7e 100644
--- a/components/ocs_http/target_esp32/client_reader.h
+++ b/components/ocs_http/target_esp32/client_reader.h
@@ -40,7 +40,7 @@ class ClientReader : private core::NonCopyable<> {
     //!
     //! @return
     //!  Number of bytes read.
-    unsigned read(char* buf, unsigned size);
+    size_t read(char* buf, size_t size);
 
 private:
     static esp_err_t handle_event_(esp_http_client_event_t* event);
diff --git a/components/ocs_http/target_esp32/response_writer.cpp b/components/ocs_http/target_esp32/response_writer.cpp
index b9e0ab37..11330f2e 100644
--- a/components/ocs_http/target_esp32/response_writer.cpp
+++ b/components/ocs_http/target_esp32/response_writer.cpp
@@ -21,7 +21,7 @@ ResponseWriter::ResponseWriter(httpd_req_t& req)
     , header_(req) {
 }
 
-status::StatusCode ResponseWriter::write(const void* data, unsigned size) {
+status::StatusCode ResponseWriter::write(const void* data, size_t size) {
     if (header_.chunked()) {
         const auto err =
             httpd_resp_send_chunk(&req_, static_cast<const char*>(data), size);
diff --git a/components/ocs_http/target_esp32/response_writer.h b/components/ocs_http/target_esp32/response_writer.h
index 096eb91d..b392f97c 100644
--- a/components/ocs_http/target_esp32/response_writer.h
+++ b/components/ocs_http/target_esp32/response_writer.h
@@ -23,7 +23,7 @@ class ResponseWriter : public IResponseWriter, private core::NonCopyable<> {
     explicit ResponseWriter(httpd_req_t& req);
 
     //! Write @p size bytes of @p data to the underlying request.
-    status::StatusCode write(const void* data, unsigned size) override;
+    status::StatusCode write(const void* data, size_t size) override;
 
     //! Write HTTP status code.
     status::StatusCode write_status(StatusCode) override;
diff --git a/components/ocs_http/target_esp32/server.h b/components/ocs_http/target_esp32/server.h
index fe5e9691..a2c6f973 100644
--- a/components/ocs_http/target_esp32/server.h
+++ b/components/ocs_http/target_esp32/server.h
@@ -23,10 +23,10 @@ class Server : public IServer,
 public:
     struct Params {
         //! TCP port to accept incoming connections.
-        unsigned server_port { 80 };
+        uint8_t server_port { 80 };
 
         //! Maximum allowed URI handlers.
-        unsigned max_uri_handlers { 32 };
+        uint8_t max_uri_handlers { 32 };
     };
 
     //! Initialize.
diff --git a/components/ocs_http/test/target_esp32/test_server.cpp b/components/ocs_http/test/target_esp32/test_server.cpp
index 3342e3c4..c34e29ef 100644
--- a/components/ocs_http/test/target_esp32/test_server.cpp
+++ b/components/ocs_http/test/target_esp32/test_server.cpp
@@ -81,7 +81,7 @@ TEST_CASE("Start HTTP server: WiFi invalid credentials", "[ocs_http], [server]")
 
 #ifdef CONFIG_OCS_TEST_UNIT_WIFI_STA_ENABLED
 TEST_CASE("Start HTTP server: WiFi valid credentials", "[ocs_http], [server]") {
-    const unsigned server_port = 80;
+    const uint8_t server_port = 80;
 
     Router router;
     Server server(router,
@@ -152,7 +152,7 @@ TEST_CASE("Start HTTP server: WiFi valid credentials", "[ocs_http], [server]") {
 
 TEST_CASE("Start HTTP server: chunked response", "[ocs_http], [server]") {
     struct TestStreamReader : public core::IStreamReader {
-        TestStreamReader(const char* response, unsigned chunk_size)
+        TestStreamReader(const char* response, size_t chunk_size)
             : response_(response)
             , chunk_size_(chunk_size) {
         }
@@ -169,7 +169,7 @@ TEST_CASE("Start HTTP server: chunked response", "[ocs_http], [server]") {
             return status::StatusCode::OK;
         }
 
-        status::StatusCode read(void* data, unsigned& size) override {
+        status::StatusCode read(void* data, size_t& size) override {
             if (pos_ == response_.size()) {
                 return status::StatusCode::NoData;
             }
@@ -185,12 +185,12 @@ TEST_CASE("Start HTTP server: chunked response", "[ocs_http], [server]") {
 
     private:
         const std::string response_;
-        const unsigned chunk_size_ { 0 };
+        const size_t chunk_size_ { 0 };
 
-        unsigned pos_ { 0 };
+        size_t pos_ { 0 };
     };
 
-    const unsigned server_port = 80;
+    const uint8_t server_port = 80;
 
     Router router;
     Server server(router,
diff --git a/components/ocs_io/i2c/itransceiver.h b/components/ocs_io/i2c/itransceiver.h
index 012fdb90..46fcc0d6 100644
--- a/components/ocs_io/i2c/itransceiver.h
+++ b/components/ocs_io/i2c/itransceiver.h
@@ -24,7 +24,7 @@ class ITransceiver {
     //!  - @p timeout - interval to wait for the operation to complete,
     //!       -1 means wait forever.
     virtual status::StatusCode
-    send(const uint8_t* buf, unsigned size, system::Time timeout) = 0;
+    send(const uint8_t* buf, size_t size, system::Time timeout) = 0;
 
     //! Receive data from the I2C device.
     //!
@@ -33,7 +33,7 @@ class ITransceiver {
     //!  - @p timeout - interval to wait for the operation to complete,
     //!       -1 means wait forever.
     virtual status::StatusCode
-    receive(uint8_t* buf, unsigned size, system::Time timeout) = 0;
+    receive(uint8_t* buf, size_t size, system::Time timeout) = 0;
 };
 
 } // namespace i2c
diff --git a/components/ocs_io/i2c/target_esp32/master_transceiver.cpp b/components/ocs_io/i2c/target_esp32/master_transceiver.cpp
index 4d63e4a5..050e04e6 100644
--- a/components/ocs_io/i2c/target_esp32/master_transceiver.cpp
+++ b/components/ocs_io/i2c/target_esp32/master_transceiver.cpp
@@ -34,7 +34,7 @@ MasterTransceiver::MasterTransceiver(MasterTransceiver::DevicePtr device, const
 }
 
 status::StatusCode
-MasterTransceiver::send(const uint8_t* buf, unsigned size, system::Time timeout) {
+MasterTransceiver::send(const uint8_t* buf, size_t size, system::Time timeout) {
     if (timeout > 0 && timeout < system::Duration::millisecond) {
         return status::StatusCode::InvalidArg;
     }
@@ -59,7 +59,7 @@ MasterTransceiver::send(const uint8_t* buf, unsigned size, system::Time timeout)
 }
 
 status::StatusCode
-MasterTransceiver::receive(uint8_t* buf, unsigned size, system::Time timeout) {
+MasterTransceiver::receive(uint8_t* buf, size_t size, system::Time timeout) {
     if (timeout > 0 && timeout < system::Duration::millisecond) {
         return status::StatusCode::InvalidArg;
     }
diff --git a/components/ocs_io/i2c/target_esp32/master_transceiver.h b/components/ocs_io/i2c/target_esp32/master_transceiver.h
index d9187000..f3c479d2 100644
--- a/components/ocs_io/i2c/target_esp32/master_transceiver.h
+++ b/components/ocs_io/i2c/target_esp32/master_transceiver.h
@@ -31,11 +31,11 @@ class MasterTransceiver : public ITransceiver, private core::NonCopyable<> {
 
     //! Send data to the I2C device.
     status::StatusCode
-    send(const uint8_t* buf, unsigned size, system::Time timeout = -1) override;
+    send(const uint8_t* buf, size_t size, system::Time timeout = -1) override;
 
     //! Receive data from the I2C device.
     status::StatusCode
-    receive(uint8_t* buf, unsigned size, system::Time timeout = -1) override;
+    receive(uint8_t* buf, size_t size, system::Time timeout = -1) override;
 
 private:
     const std::string id_;
diff --git a/components/ocs_io/spi/itransceiver.h b/components/ocs_io/spi/itransceiver.h
index 3a9bebe4..1fc85c5a 100644
--- a/components/ocs_io/spi/itransceiver.h
+++ b/components/ocs_io/spi/itransceiver.h
@@ -22,9 +22,9 @@ class ITransceiver {
     //!  - @p send_buf - sending data, should be at least @p send_buf_size bytes long.
     //!  - @p recv_buf - receiving data, should be at least @p recv_buf_size bytes long.
     virtual status::StatusCode transceive(const uint8_t* send_buf,
-                                          unsigned send_buf_size,
+                                          size_t send_buf_size,
                                           uint8_t* recv_buf,
-                                          unsigned recv_buf_size) = 0;
+                                          size_t recv_buf_size) = 0;
 };
 
 } // namespace spi
diff --git a/components/ocs_io/spi/target_esp32/master_transceiver.cpp b/components/ocs_io/spi/target_esp32/master_transceiver.cpp
index de982162..a9ddb20e 100644
--- a/components/ocs_io/spi/target_esp32/master_transceiver.cpp
+++ b/components/ocs_io/spi/target_esp32/master_transceiver.cpp
@@ -35,9 +35,9 @@ MasterTransceiver::MasterTransceiver(MasterTransceiver::DevicePtr device, const
 }
 
 status::StatusCode MasterTransceiver::transceive(const uint8_t* send_buf,
-                                                 unsigned send_buf_size,
+                                                 size_t send_buf_size,
                                                  uint8_t* recv_buf,
-                                                 unsigned recv_buf_size) {
+                                                 size_t recv_buf_size) {
     spi_transaction_t transaction;
     memset(&transaction, 0, sizeof(transaction));
 
diff --git a/components/ocs_io/spi/target_esp32/master_transceiver.h b/components/ocs_io/spi/target_esp32/master_transceiver.h
index 28f77137..5ba85a70 100644
--- a/components/ocs_io/spi/target_esp32/master_transceiver.h
+++ b/components/ocs_io/spi/target_esp32/master_transceiver.h
@@ -31,9 +31,9 @@ class MasterTransceiver : public ITransceiver, private core::NonCopyable<> {
 
     //! Send/receive data over SPI bus.
     status::StatusCode transceive(const uint8_t* send_buf,
-                                  unsigned send_buf_size,
+                                  size_t send_buf_size,
                                   uint8_t* recv_buf,
-                                  unsigned recv_buf_size) override;
+                                  size_t recv_buf_size) override;
 
 private:
     const std::string id_;
diff --git a/components/ocs_io/test/adc/target_esp32/test_oneshot_store.cpp b/components/ocs_io/test/adc/target_esp32/test_oneshot_store.cpp
index 18f6656d..2b32716c 100644
--- a/components/ocs_io/test/adc/target_esp32/test_oneshot_store.cpp
+++ b/components/ocs_io/test/adc/target_esp32/test_oneshot_store.cpp
@@ -25,9 +25,9 @@ TEST_CASE("Oneshot ADC store: register maximum number of ADC",
     for (const auto& unit : units) {
         OneshotStore store(unit, ADC_ATTEN_DB_12, ADC_BITWIDTH_10);
 
-        const unsigned count = SOC_ADC_CHANNEL_NUM(unit);
+        const size_t count = SOC_ADC_CHANNEL_NUM(unit);
 
-        for (unsigned n = 0; n < count; ++n) {
+        for (size_t n = 0; n < count; ++n) {
             const Channel channel = static_cast<Channel>(n);
             TEST_ASSERT_NOT_NULL(store.add(channel));
         }
@@ -59,9 +59,9 @@ TEST_CASE("Oneshot ADC store: register overflow", "[ocs_io], [adc_oneshot_store]
     for (const auto& unit : units) {
         OneshotStore store(unit, ADC_ATTEN_DB_12, ADC_BITWIDTH_10);
 
-        const unsigned count = SOC_ADC_CHANNEL_NUM(unit);
+        const size_t count = SOC_ADC_CHANNEL_NUM(unit);
 
-        for (unsigned n = 0; n < count; ++n) {
+        for (size_t n = 0; n < count; ++n) {
             const Channel channel = static_cast<Channel>(n);
             TEST_ASSERT_NOT_NULL(store.add(channel));
         }
diff --git a/components/ocs_net/mdns_config.cpp b/components/ocs_net/mdns_config.cpp
index 7287d1e3..6f766e7e 100644
--- a/components/ocs_net/mdns_config.cpp
+++ b/components/ocs_net/mdns_config.cpp
@@ -23,11 +23,11 @@ const char* log_tag = "mdns_config";
 MdnsConfig::MdnsConfig(storage::IStorage& storage, const system::DeviceInfo& device_info)
     : storage_(storage) {
     memset(hostname_, 0, sizeof(hostname_));
-    auto code =
-        algo::StorageOps::prob_read(storage_, hostname_key_, hostname_, max_hostname_len);
+
+    auto code = algo::StorageOps::prob_read(storage_, hostname_key_, hostname_,
+                                            max_hostname_len_);
     if (code != status::StatusCode::OK) {
-        memcpy(hostname_, device_info.get_fw_name(),
-               std::min(max_hostname_len, strlen(device_info.get_fw_name())));
+        strncpy(hostname_, device_info.get_fw_name(), sizeof(hostname_));
     }
 }
 
@@ -45,7 +45,7 @@ const char* MdnsConfig::get_hostname() const {
 }
 
 status::StatusCode MdnsConfig::configure(const char* hostname) {
-    if (strlen(hostname) > max_hostname_len) {
+    if (strlen(hostname) > max_hostname_len_) {
         return status::StatusCode::InvalidArg;
     }
 
diff --git a/components/ocs_net/mdns_config.h b/components/ocs_net/mdns_config.h
index 1556b1c2..f1b70db3 100644
--- a/components/ocs_net/mdns_config.h
+++ b/components/ocs_net/mdns_config.h
@@ -15,9 +15,6 @@ namespace net {
 
 class MdnsConfig : public storage::IConfig, private core::NonCopyable<> {
 public:
-    // Maximum length of the mDNS hostname.
-    static constexpr unsigned max_hostname_len = 31;
-
     //! Initialize.
     //!
     //! @params
@@ -45,7 +42,9 @@ class MdnsConfig : public storage::IConfig, private core::NonCopyable<> {
 
     storage::IStorage& storage_;
 
-    char hostname_[max_hostname_len + 1];
+    static constexpr uint8_t max_hostname_len_ = 31;
+
+    char hostname_[max_hostname_len_ + 1];
 };
 
 } // namespace net
diff --git a/components/ocs_net/target_esp32/sta_network.h b/components/ocs_net/target_esp32/sta_network.h
index 359cb646..037cecf9 100644
--- a/components/ocs_net/target_esp32/sta_network.h
+++ b/components/ocs_net/target_esp32/sta_network.h
@@ -66,7 +66,7 @@ class StaNetwork : public INetwork, public IStaNetwork, private core::NonCopyabl
 
     core::StaticEventGroup event_group_;
 
-    unsigned retry_count_ { 0 };
+    uint8_t retry_count_ { 0 };
 };
 
 } // namespace net
diff --git a/components/ocs_onewire/bus.cpp b/components/ocs_onewire/bus.cpp
index b659c5bb..3ab9bfbf 100644
--- a/components/ocs_onewire/bus.cpp
+++ b/components/ocs_onewire/bus.cpp
@@ -95,7 +95,7 @@ status::StatusCode Bus::read_bit(uint8_t& bit) {
 }
 
 status::StatusCode Bus::write_byte(uint8_t byte) {
-    for (unsigned n = 0; n < bits_in_byte_; ++n) {
+    for (uint8_t n = 0; n < bits_in_byte_; ++n) {
         const uint8_t bit = byte % 2;
         OCS_STATUS_RETURN_ON_ERROR(write_bit(bit));
 
@@ -106,7 +106,7 @@ status::StatusCode Bus::write_byte(uint8_t byte) {
 }
 
 status::StatusCode Bus::read_byte(uint8_t& byte) {
-    for (unsigned n = 0; n < bits_in_byte_; ++n) {
+    for (uint8_t n = 0; n < bits_in_byte_; ++n) {
         uint8_t bit = 0;
         OCS_STATUS_RETURN_ON_ERROR(read_bit(bit));
 
@@ -120,22 +120,22 @@ status::StatusCode Bus::read_byte(uint8_t& byte) {
     return status::StatusCode::OK;
 }
 
-status::StatusCode Bus::read_bytes(uint8_t* buf, unsigned size) {
+status::StatusCode Bus::read_bytes(uint8_t* buf, size_t size) {
     OCS_STATUS_RETURN_ON_FALSE(buf, status::StatusCode::InvalidArg);
     OCS_STATUS_RETURN_ON_FALSE(size, status::StatusCode::InvalidArg);
 
-    for (unsigned n = 0; n < size; ++n) {
+    for (size_t n = 0; n < size; ++n) {
         OCS_STATUS_RETURN_ON_ERROR(read_byte(buf[n]));
     }
 
     return status::StatusCode::OK;
 }
 
-status::StatusCode Bus::write_bytes(const uint8_t* buf, unsigned size) {
+status::StatusCode Bus::write_bytes(const uint8_t* buf, size_t size) {
     OCS_STATUS_RETURN_ON_FALSE(buf, status::StatusCode::InvalidArg);
     OCS_STATUS_RETURN_ON_FALSE(size, status::StatusCode::InvalidArg);
 
-    for (unsigned n = 0; n < size; ++n) {
+    for (size_t n = 0; n < size; ++n) {
         OCS_STATUS_RETURN_ON_ERROR(write_byte(buf[n]));
     }
 
diff --git a/components/ocs_onewire/bus.h b/components/ocs_onewire/bus.h
index 252530b7..2145a9f5 100644
--- a/components/ocs_onewire/bus.h
+++ b/components/ocs_onewire/bus.h
@@ -72,13 +72,13 @@ class Bus : private core::NonCopyable<> {
     //!
     //! @remarks
     //!  - @p buf should be at least @p size bytes long.
-    status::StatusCode read_bytes(uint8_t* buf, unsigned size);
+    status::StatusCode read_bytes(uint8_t* buf, size_t size);
 
     //! Write @p size bytes from @p buf to the bus.
     //!
     //! @remarks
     //!  - @p buf should be at least @p size bytes long.
-    status::StatusCode write_bytes(const uint8_t* buf, unsigned size);
+    status::StatusCode write_bytes(const uint8_t* buf, size_t size);
 
 private:
     status::StatusCode write_bit_one_();
@@ -86,7 +86,7 @@ class Bus : private core::NonCopyable<> {
 
     const Params params_;
 
-    const unsigned bits_in_byte_ = 8;
+    const uint8_t bits_in_byte_ = 8;
 
     system::Time reset_remain_time_slot_ { 0 };
     system::Time write_remain_time_slot_ { 0 };
diff --git a/components/ocs_onewire/crc.cpp b/components/ocs_onewire/crc.cpp
index 6a27b3eb..c6cff348 100644
--- a/components/ocs_onewire/crc.cpp
+++ b/components/ocs_onewire/crc.cpp
@@ -9,7 +9,7 @@
 namespace ocs {
 namespace onewire {
 
-uint8_t calculate_crc(const uint8_t* buf, unsigned size) {
+uint8_t calculate_crc(const uint8_t* buf, size_t size) {
     return algo::CrcOps::crc8(buf, size, 0x00, 0x8C, algo::CrcOps::BitOrder::LSB);
 }
 
diff --git a/components/ocs_onewire/crc.h b/components/ocs_onewire/crc.h
index f10574cc..934d451e 100644
--- a/components/ocs_onewire/crc.h
+++ b/components/ocs_onewire/crc.h
@@ -5,6 +5,7 @@
 
 #pragma once
 
+#include <cstddef>
 #include <cstdint>
 
 namespace ocs {
@@ -18,7 +19,7 @@ namespace onewire {
 //! @references
 //!  https://stackoverflow.com/questions/29214301/ios-how-to-calculate-crc-8-dallas-maxim-of-nsdata
 //!  https://stackoverflow.com/questions/74775595/maxim-dow-crc-algorithm-cannot-re-create-example-in-application-note
-uint8_t calculate_crc(const uint8_t* buf, unsigned size);
+uint8_t calculate_crc(const uint8_t* buf, size_t size);
 
 } // namespace onewire
 } // namespace ocs
diff --git a/components/ocs_onewire/rom_code_scanner.cpp b/components/ocs_onewire/rom_code_scanner.cpp
index 46ffd9eb..7f9087a6 100644
--- a/components/ocs_onewire/rom_code_scanner.cpp
+++ b/components/ocs_onewire/rom_code_scanner.cpp
@@ -46,7 +46,7 @@ void RomCodeScanner::reset() {
     conflict_count_ = 0;
 }
 
-status::StatusCode RomCodeScanner::scan_(uint8_t* buf, unsigned size) {
+status::StatusCode RomCodeScanner::scan_(uint8_t* buf, size_t size) {
     for (int n = 0; n < size * bits_in_byte_; ++n) {
         uint8_t bit1 = 0;
         OCS_STATUS_RETURN_ON_ERROR(bus_.read_bit(bit1));
@@ -70,8 +70,8 @@ status::StatusCode RomCodeScanner::scan_(uint8_t* buf, unsigned size) {
             }
         }
 
-        const unsigned byte_pos = n / bits_in_byte_;
-        const unsigned bit_pos = n % bits_in_byte_;
+        const size_t byte_pos = n / bits_in_byte_;
+        const size_t bit_pos = n % bits_in_byte_;
 
         if (bit) {
             buf[byte_pos] |= algo::BitOps::mask(bit_pos);
@@ -123,8 +123,8 @@ uint8_t RomCodeScanner::handle_discrepancy_(const uint8_t* buf, int position) {
     // Follow to the previous path.
     configASSERT(prev_discrepancy_ >= 0);
 
-    const unsigned byte_pos = prev_discrepancy_ / bits_in_byte_;
-    const unsigned bit_pos = prev_discrepancy_ % bits_in_byte_;
+    const size_t byte_pos = prev_discrepancy_ / bits_in_byte_;
+    const size_t bit_pos = prev_discrepancy_ % bits_in_byte_;
 
     prev_discrepancy_ = position;
 
diff --git a/components/ocs_onewire/rom_code_scanner.h b/components/ocs_onewire/rom_code_scanner.h
index 90e4b1e2..713e63b8 100644
--- a/components/ocs_onewire/rom_code_scanner.h
+++ b/components/ocs_onewire/rom_code_scanner.h
@@ -28,17 +28,17 @@ class RomCodeScanner : private core::NonCopyable<> {
     void reset();
 
 private:
-    status::StatusCode scan_(uint8_t* buf, unsigned size);
+    status::StatusCode scan_(uint8_t* buf, size_t size);
     uint8_t handle_discrepancy_(const uint8_t* buf, int position);
 
-    static constexpr unsigned bits_in_byte_ = 8;
+    static constexpr uint8_t bits_in_byte_ = 8;
 
     Bus& bus_;
 
     bool finished_ { false };
     int prev_discrepancy_ { -1 };
     int curr_discrepancy_ { -1 };
-    unsigned conflict_count_ { 0 };
+    size_t conflict_count_ { 0 };
 };
 
 } // namespace onewire
diff --git a/components/ocs_onewire/serial_number_to_str.h b/components/ocs_onewire/serial_number_to_str.h
index d8065c8d..6a0fd099 100644
--- a/components/ocs_onewire/serial_number_to_str.h
+++ b/components/ocs_onewire/serial_number_to_str.h
@@ -16,7 +16,7 @@ namespace onewire {
 //! Format sensor serial number to string.
 class serial_number_to_str : private core::NonCopyable<> {
 public:
-    static constexpr unsigned str_length = strlen("AA:BB:CC:DD:EE:FF");
+    static constexpr size_t str_length = strlen("AA:BB:CC:DD:EE:FF");
 
     //! Initialize.
     serial_number_to_str(const SerialNumber& serial_number);
diff --git a/components/ocs_pipeline/httpserver/analog_config_store_handler.cpp b/components/ocs_pipeline/httpserver/analog_config_store_handler.cpp
index bcf38346..311a5fc2 100644
--- a/components/ocs_pipeline/httpserver/analog_config_store_handler.cpp
+++ b/components/ocs_pipeline/httpserver/analog_config_store_handler.cpp
@@ -21,7 +21,7 @@ namespace httpserver {
 
 namespace {
 
-status::StatusCode send_json(http::IResponseWriter& w, cJSON* json, unsigned size) {
+status::StatusCode send_json(http::IResponseWriter& w, cJSON* json, size_t size) {
     fmt::json::DynamicFormatter json_formatter(size);
 
     const auto code = json_formatter.format(json);
diff --git a/components/ocs_pipeline/httpserver/data_handler.cpp b/components/ocs_pipeline/httpserver/data_handler.cpp
index 0fd2cb10..f2df7364 100644
--- a/components/ocs_pipeline/httpserver/data_handler.cpp
+++ b/components/ocs_pipeline/httpserver/data_handler.cpp
@@ -14,7 +14,7 @@ namespace ocs {
 namespace pipeline {
 namespace httpserver {
 
-DataHandler::DataHandler(fmt::json::IFormatter& formatter, unsigned buffer_size) {
+DataHandler::DataHandler(fmt::json::IFormatter& formatter, size_t buffer_size) {
     fanout_formatter_.reset(new (std::nothrow) fmt::json::FanoutFormatter());
     configASSERT(fanout_formatter_);
 
diff --git a/components/ocs_pipeline/httpserver/data_handler.h b/components/ocs_pipeline/httpserver/data_handler.h
index b707f36b..21330997 100644
--- a/components/ocs_pipeline/httpserver/data_handler.h
+++ b/components/ocs_pipeline/httpserver/data_handler.h
@@ -25,7 +25,7 @@ class DataHandler : public http::IHandler, private core::NonCopyable<> {
     //! @params
     //!  - @p formatter to format the data.
     //!  - @p buffer_size to hold the formatted JSON data, in bytes.
-    DataHandler(fmt::json::IFormatter& formatter, unsigned buffer_size);
+    DataHandler(fmt::json::IFormatter& formatter, size_t buffer_size);
 
     // Get data over HTTP.
     status::StatusCode serve_http(http::IResponseWriter& w, http::IRequest&) override;
diff --git a/components/ocs_pipeline/httpserver/ds18b20_handler.cpp b/components/ocs_pipeline/httpserver/ds18b20_handler.cpp
index ff65fc7d..8eee859b 100644
--- a/components/ocs_pipeline/httpserver/ds18b20_handler.cpp
+++ b/components/ocs_pipeline/httpserver/ds18b20_handler.cpp
@@ -285,8 +285,8 @@ status::StatusCode DS18B20Handler::format_sensor_(cJSON* array,
 status::StatusCode
 DS18B20Handler::handle_configuration_(http::IResponseWriter& w,
                                       http::IRequest& r,
-                                      unsigned wait_interval,
-                                      unsigned response_size,
+                                      size_t wait_interval,
+                                      size_t response_size,
                                       DS18B20Handler::HandleConfigurationFunc func) {
     const auto values = algo::UriOps::parse_query(r.get_uri());
 
@@ -480,7 +480,7 @@ status::StatusCode DS18B20Handler::erase_configuration_(cJSON* json,
     return status::StatusCode::OK;
 }
 
-status::StatusCode DS18B20Handler::send_response_(unsigned buffer_size,
+status::StatusCode DS18B20Handler::send_response_(size_t buffer_size,
                                                   cJSON* json,
                                                   http::IResponseWriter& w) {
     fmt::json::DynamicFormatter json_formatter(buffer_size);
diff --git a/components/ocs_pipeline/httpserver/ds18b20_handler.h b/components/ocs_pipeline/httpserver/ds18b20_handler.h
index 7ad0b83b..42cd5c10 100644
--- a/components/ocs_pipeline/httpserver/ds18b20_handler.h
+++ b/components/ocs_pipeline/httpserver/ds18b20_handler.h
@@ -34,10 +34,10 @@ class DS18B20Handler : private http::IHandler, private core::NonCopyable<> {
     using HandleConfigurationFunc =
         std::function<status::StatusCode(cJSON*, sensor::ds18b20::Sensor&)>;
 
-    static constexpr unsigned scan_response_buffer_size_ { 256 };
-    static constexpr unsigned read_response_buffer_size_ { 256 };
-    static constexpr unsigned write_response_buffer_size_ { 256 };
-    static constexpr unsigned erase_response_buffer_size_ { 256 };
+    static constexpr size_t scan_response_buffer_size_ { 256 };
+    static constexpr size_t read_response_buffer_size_ { 256 };
+    static constexpr size_t write_response_buffer_size_ { 256 };
+    static constexpr size_t erase_response_buffer_size_ { 256 };
 
     static constexpr TickType_t scan_wait_interval_ { pdMS_TO_TICKS(10 * 1000) };
     static constexpr TickType_t read_wait_interval_ { pdMS_TO_TICKS(5 * 1000) };
@@ -65,8 +65,8 @@ class DS18B20Handler : private http::IHandler, private core::NonCopyable<> {
 
     status::StatusCode handle_configuration_(http::IResponseWriter& w,
                                              http::IRequest& r,
-                                             unsigned wait_interval,
-                                             unsigned response_size,
+                                             size_t wait_interval,
+                                             size_t response_size,
                                              HandleConfigurationFunc func);
 
     status::StatusCode read_configuration_(cJSON* json, sensor::ds18b20::Sensor&);
@@ -87,7 +87,7 @@ class DS18B20Handler : private http::IHandler, private core::NonCopyable<> {
     status::StatusCode erase_configuration_(cJSON* json, sensor::ds18b20::Sensor& sensor);
 
     status::StatusCode
-    send_response_(unsigned buffer_size, cJSON* json, http::IResponseWriter& w);
+    send_response_(size_t buffer_size, cJSON* json, http::IResponseWriter& w);
 
     system::ISuspender& suspender_;
     sensor::ds18b20::Store& store_;
diff --git a/components/ocs_pipeline/httpserver/http_pipeline.h b/components/ocs_pipeline/httpserver/http_pipeline.h
index ad7944b7..4f07dadf 100644
--- a/components/ocs_pipeline/httpserver/http_pipeline.h
+++ b/components/ocs_pipeline/httpserver/http_pipeline.h
@@ -19,7 +19,7 @@ class HttpPipeline : private core::NonCopyable<> {
 public:
     struct DataParams {
         //! Buffer size to hold the formatted JSON data, in bytes.
-        unsigned buffer_size { 0 };
+        size_t buffer_size { 0 };
     };
 
     struct Params {
diff --git a/components/ocs_pipeline/httpserver/system_state_handler.cpp b/components/ocs_pipeline/httpserver/system_state_handler.cpp
index 076acd14..6af0540d 100644
--- a/components/ocs_pipeline/httpserver/system_state_handler.cpp
+++ b/components/ocs_pipeline/httpserver/system_state_handler.cpp
@@ -14,7 +14,7 @@ namespace ocs {
 namespace pipeline {
 namespace httpserver {
 
-SystemStateHandler::SystemStateHandler(unsigned response_size) {
+SystemStateHandler::SystemStateHandler(size_t response_size) {
     state_json_formatter_.reset(new (std::nothrow) jsonfmt::SystemStateFormatter());
     configASSERT(state_json_formatter_);
 
diff --git a/components/ocs_pipeline/httpserver/system_state_handler.h b/components/ocs_pipeline/httpserver/system_state_handler.h
index 824a2097..b6b80735 100644
--- a/components/ocs_pipeline/httpserver/system_state_handler.h
+++ b/components/ocs_pipeline/httpserver/system_state_handler.h
@@ -23,7 +23,7 @@ class SystemStateHandler : public http::IHandler, private core::NonCopyable<> {
     //!
     //! @params
     //!  - @p response_size - system state response size, in bytes.
-    SystemStateHandler(unsigned response_size);
+    explicit SystemStateHandler(size_t response_size);
 
     // Get system state over HTTP.
     status::StatusCode serve_http(http::IResponseWriter& w, http::IRequest&) override;
diff --git a/components/ocs_pipeline/httpserver/web_gui_pipeline.h b/components/ocs_pipeline/httpserver/web_gui_pipeline.h
index 83c21ad4..92958977 100644
--- a/components/ocs_pipeline/httpserver/web_gui_pipeline.h
+++ b/components/ocs_pipeline/httpserver/web_gui_pipeline.h
@@ -36,7 +36,7 @@ class WebGuiPipeline : private http::IHandler, private core::NonCopyable<> {
     status::StatusCode handle_root_(http::IResponseWriter& w);
     status::StatusCode handle_file_(http::IResponseWriter& w, const char* filename);
 
-    static constexpr unsigned buffer_size_ = 1024;
+    static constexpr size_t buffer_size_ = 1024;
 
     const std::string mount_point_;
 
diff --git a/components/ocs_pipeline/jsonfmt/system_state_formatter.cpp b/components/ocs_pipeline/jsonfmt/system_state_formatter.cpp
index f3053e16..9036f613 100644
--- a/components/ocs_pipeline/jsonfmt/system_state_formatter.cpp
+++ b/components/ocs_pipeline/jsonfmt/system_state_formatter.cpp
@@ -53,7 +53,7 @@ status::StatusCode format_task_state(fmt::json::CjsonObjectFormatter& formatter,
             return status::StatusCode::NoMem;
         }
 
-        const unsigned decimal_places = 2;
+        const uint8_t decimal_places = 2;
         const auto value = static_cast<double>(state.ulRunTimeCounter) / total_time;
         const auto multiplier = std::pow(10.0, decimal_places);
         const auto relative = std::ceil(value * multiplier) / multiplier;
diff --git a/components/ocs_scheduler/async_func_scheduler.cpp b/components/ocs_scheduler/async_func_scheduler.cpp
index 9c640bc7..71684cfc 100644
--- a/components/ocs_scheduler/async_func_scheduler.cpp
+++ b/components/ocs_scheduler/async_func_scheduler.cpp
@@ -19,7 +19,7 @@ const char* log_tag = "async_func_scheduler";
 
 } // namespace
 
-AsyncFuncScheduler::AsyncFuncScheduler(unsigned max_event_count)
+AsyncFuncScheduler::AsyncFuncScheduler(size_t max_event_count)
     : max_event_count_(max_event_count) {
     configASSERT(max_event_count_);
 
diff --git a/components/ocs_scheduler/async_func_scheduler.h b/components/ocs_scheduler/async_func_scheduler.h
index 4381713b..9e404b67 100644
--- a/components/ocs_scheduler/async_func_scheduler.h
+++ b/components/ocs_scheduler/async_func_scheduler.h
@@ -27,7 +27,7 @@ class AsyncFuncScheduler : public ITask, private core::NonCopyable<> {
     //! @params
     //!  - @p max_event_count - maximum number of asynchronous events that can be enqueued
     //!    before run() is called.
-    explicit AsyncFuncScheduler(unsigned max_event_count);
+    explicit AsyncFuncScheduler(size_t max_event_count);
 
     //! Run scheduled events.
     status::StatusCode run() override;
@@ -39,7 +39,7 @@ class AsyncFuncScheduler : public ITask, private core::NonCopyable<> {
     FuturePtr add(Func func);
 
 private:
-    const unsigned max_event_count_ { 0 };
+    const size_t max_event_count_ { 0 };
 
     using Queue = std::vector<Func>;
     using QueuePtr = std::shared_ptr<Queue>;
diff --git a/components/ocs_scheduler/async_task_scheduler.cpp b/components/ocs_scheduler/async_task_scheduler.cpp
index 8f1628b8..2747087a 100644
--- a/components/ocs_scheduler/async_task_scheduler.cpp
+++ b/components/ocs_scheduler/async_task_scheduler.cpp
@@ -22,7 +22,7 @@ AsyncTaskScheduler::AsyncTaskScheduler(IDelayEstimator& estimator, const char* i
     , estimator_(estimator) {
 }
 
-unsigned AsyncTaskScheduler::max_count() const {
+size_t AsyncTaskScheduler::max_count() const {
     //!  8 high bits are used by the FreeRTOS itself.
     return (sizeof(EventBits_t) * 8) - 8;
 }
diff --git a/components/ocs_scheduler/async_task_scheduler.h b/components/ocs_scheduler/async_task_scheduler.h
index 247be6bd..8bdd7b11 100644
--- a/components/ocs_scheduler/async_task_scheduler.h
+++ b/components/ocs_scheduler/async_task_scheduler.h
@@ -28,7 +28,7 @@ class AsyncTaskScheduler : public ITaskScheduler, private core::NonCopyable<> {
     AsyncTaskScheduler(IDelayEstimator& estimator, const char* id);
 
     //! Maximum number of tasks to which a scheduler can deliver asynchronous events.
-    unsigned max_count() const override;
+    size_t max_count() const override;
 
     //! Add task to be executed once per interval.
     //!
diff --git a/components/ocs_scheduler/itask_scheduler.h b/components/ocs_scheduler/itask_scheduler.h
index 464b5153..e1226523 100644
--- a/components/ocs_scheduler/itask_scheduler.h
+++ b/components/ocs_scheduler/itask_scheduler.h
@@ -18,7 +18,7 @@ class ITaskScheduler {
     virtual ~ITaskScheduler() = default;
 
     //! Return the maximum number of tasks a scheduler can handle.
-    virtual unsigned max_count() const = 0;
+    virtual size_t max_count() const = 0;
 
     //! Add task to be executed periodically once per interval.
     //!
diff --git a/components/ocs_scheduler/periodic_task_scheduler.cpp b/components/ocs_scheduler/periodic_task_scheduler.cpp
index c1497e6c..4f98d268 100644
--- a/components/ocs_scheduler/periodic_task_scheduler.cpp
+++ b/components/ocs_scheduler/periodic_task_scheduler.cpp
@@ -19,7 +19,7 @@ namespace scheduler {
 PeriodicTaskScheduler::PeriodicTaskScheduler(system::IClock& clock,
                                              IDelayEstimator& estimator,
                                              const char* id,
-                                             unsigned max_count)
+                                             size_t max_count)
     : max_count_(max_count)
     , log_tag_(id)
     , clock_(clock)
@@ -27,7 +27,7 @@ PeriodicTaskScheduler::PeriodicTaskScheduler(system::IClock& clock,
     configASSERT(max_count_);
 }
 
-unsigned PeriodicTaskScheduler::max_count() const {
+size_t PeriodicTaskScheduler::max_count() const {
     return max_count_;
 }
 
diff --git a/components/ocs_scheduler/periodic_task_scheduler.h b/components/ocs_scheduler/periodic_task_scheduler.h
index c0d571df..99d3ec07 100644
--- a/components/ocs_scheduler/periodic_task_scheduler.h
+++ b/components/ocs_scheduler/periodic_task_scheduler.h
@@ -32,10 +32,10 @@ class PeriodicTaskScheduler : public ITaskScheduler, private core::NonCopyable<>
     PeriodicTaskScheduler(system::IClock& clock,
                           IDelayEstimator& estimator,
                           const char* id,
-                          unsigned max_count);
+                          size_t max_count);
 
     //! Return the maximum configured number of tasks a scheduler can handle.
-    unsigned max_count() const override;
+    size_t max_count() const override;
 
     //! Add task to be executed periodically once per interval.
     //!
@@ -96,7 +96,7 @@ class PeriodicTaskScheduler : public ITaskScheduler, private core::NonCopyable<>
 
     void run_();
 
-    const unsigned max_count_ { 0 };
+    const size_t max_count_ { 0 };
     const std::string log_tag_;
 
     system::Time total_ts_min_ { INT64_MAX };
diff --git a/components/ocs_scheduler/test/test_async_task_scheduler.cpp b/components/ocs_scheduler/test/test_async_task_scheduler.cpp
index 7c0de5a3..81fbcbc4 100644
--- a/components/ocs_scheduler/test/test_async_task_scheduler.cpp
+++ b/components/ocs_scheduler/test/test_async_task_scheduler.cpp
@@ -73,14 +73,14 @@ TEST_CASE("Async task scheduler: register maximum tasks",
     using TaskPtr = std::shared_ptr<test::TestTask>;
     std::vector<TaskPtr> tasks;
 
-    for (unsigned n = 0; n < scheduler.max_count(); ++n) {
+    for (size_t n = 0; n < scheduler.max_count(); ++n) {
         TaskPtr task(new (std::nothrow) test::TestTask(status::StatusCode::OK));
         TEST_ASSERT_NOT_NULL(task);
 
         tasks.push_back(task);
     }
 
-    for (unsigned n = 0; n < tasks.size(); ++n) {
+    for (size_t n = 0; n < tasks.size(); ++n) {
         const std::string task_id = std::string("test_task_") + std::to_string(n);
 
         TEST_ASSERT_EQUAL(status::StatusCode::OK,
@@ -111,7 +111,7 @@ TEST_CASE("Async task scheduler: register maximum tasks: some failed",
     using TaskPtr = std::shared_ptr<test::TestTask>;
     std::vector<TaskPtr> tasks;
 
-    for (unsigned n = 0; n < scheduler.max_count(); ++n) {
+    for (size_t n = 0; n < scheduler.max_count(); ++n) {
         status::StatusCode code = status::StatusCode::OK;
         if (n % 2 == 0) {
             code = status::StatusCode::Error;
@@ -123,7 +123,7 @@ TEST_CASE("Async task scheduler: register maximum tasks: some failed",
         tasks.push_back(task);
     }
 
-    for (unsigned n = 0; n < tasks.size(); ++n) {
+    for (size_t n = 0; n < tasks.size(); ++n) {
         const std::string task_id = std::string("test_task_") + std::to_string(n);
 
         TEST_ASSERT_EQUAL(status::StatusCode::OK,
@@ -154,14 +154,14 @@ TEST_CASE("Async task scheduler: register tasks overflow",
     using TaskPtr = std::shared_ptr<test::TestTask>;
     std::vector<TaskPtr> tasks;
 
-    for (unsigned n = 0; n < scheduler.max_count(); ++n) {
+    for (size_t n = 0; n < scheduler.max_count(); ++n) {
         TaskPtr task(new (std::nothrow) test::TestTask(status::StatusCode::OK));
         TEST_ASSERT_NOT_NULL(task);
 
         tasks.push_back(task);
     }
 
-    for (unsigned n = 0; n < tasks.size(); ++n) {
+    for (size_t n = 0; n < tasks.size(); ++n) {
         const std::string task_id = std::string("test_task_") + std::to_string(n);
 
         TEST_ASSERT_EQUAL(status::StatusCode::OK,
diff --git a/components/ocs_scheduler/test/test_periodic_task_scheduler.cpp b/components/ocs_scheduler/test/test_periodic_task_scheduler.cpp
index 3e84ef8b..e65d3940 100644
--- a/components/ocs_scheduler/test/test_periodic_task_scheduler.cpp
+++ b/components/ocs_scheduler/test/test_periodic_task_scheduler.cpp
@@ -279,7 +279,7 @@ TEST_CASE("Periodic task scheduler: add-remove-run",
 
 TEST_CASE("Periodic task scheduler: add multiple tasks",
           "[ocs_scheduler], [periodic_task_scheduler]") {
-    const unsigned task_count = 10;
+    const size_t task_count = 10;
     const TickType_t delay = pdMS_TO_TICKS(10);
     const system::Time interval = system::Duration::second;
 
@@ -294,14 +294,14 @@ TEST_CASE("Periodic task scheduler: add multiple tasks",
     using TaskList = std::vector<TaskPtr>;
     TaskList tasks;
 
-    for (unsigned n = 0; n < task_count; ++n) {
+    for (size_t n = 0; n < task_count; ++n) {
         TaskPtr task(new (std::nothrow) test::TestTask(status::StatusCode::OK));
         TEST_ASSERT_NOT_NULL(task);
 
         tasks.push_back(task);
     }
 
-    for (unsigned n = 0; n < task_count; ++n) {
+    for (size_t n = 0; n < task_count; ++n) {
         const std::string id = "test_task_" + std::to_string(n);
         TEST_ASSERT_EQUAL(status::StatusCode::OK,
                           task_scheduler.add(*tasks[n], id.c_str(), interval));
@@ -396,7 +396,7 @@ TEST_CASE("Periodic task scheduler: max number of tasks overflow: active",
 
 TEST_CASE("Periodic task scheduler: add/remove multiple tasks",
           "[ocs_scheduler], [periodic_task_scheduler]") {
-    const unsigned task_count = 10;
+    const size_t task_count = 10;
     const TickType_t delay = pdMS_TO_TICKS(10);
     const system::Time interval = system::Duration::second;
 
@@ -411,14 +411,14 @@ TEST_CASE("Periodic task scheduler: add/remove multiple tasks",
     using TaskList = std::vector<TaskPtr>;
     TaskList tasks;
 
-    for (unsigned n = 0; n < task_count; ++n) {
+    for (size_t n = 0; n < task_count; ++n) {
         TaskPtr task(new (std::nothrow) test::TestTask(status::StatusCode::OK));
         TEST_ASSERT_NOT_NULL(task);
 
         tasks.push_back(task);
     }
 
-    for (unsigned n = 0; n < task_count; ++n) {
+    for (size_t n = 0; n < task_count; ++n) {
         const std::string id = "test_task_" + std::to_string(n);
         TEST_ASSERT_EQUAL(status::StatusCode::OK,
                           task_scheduler.add(*tasks[n], id.c_str(), interval));
@@ -433,7 +433,7 @@ TEST_CASE("Periodic task scheduler: add/remove multiple tasks",
         task->reset(status::StatusCode::OK);
     }
 
-    for (unsigned n = task_count / 2; n < task_count; ++n) {
+    for (size_t n = task_count / 2; n < task_count; ++n) {
         const std::string id = "test_task_" + std::to_string(n);
         TEST_ASSERT_EQUAL(status::StatusCode::OK, task_scheduler.remove(id.c_str()));
     }
@@ -443,17 +443,17 @@ TEST_CASE("Periodic task scheduler: add/remove multiple tasks",
         TEST_ASSERT_EQUAL(0, task->run_call_count());
     }
 
-    for (unsigned n = task_count / 2; n < task_count; ++n) {
+    for (size_t n = task_count / 2; n < task_count; ++n) {
         const std::string id = "test_task_" + std::to_string(n);
         TEST_ASSERT_EQUAL(status::StatusCode::OK,
                           task_scheduler.add(*tasks[n], id.c_str(), interval));
     }
     TEST_ASSERT_EQUAL(status::StatusCode::OK, task_scheduler.run());
-    for (unsigned n = 0; n < task_count / 2; ++n) {
+    for (size_t n = 0; n < task_count / 2; ++n) {
         TEST_ASSERT_EQUAL(0, tasks[n]->run_call_count());
     }
     // The first run is always allowed.
-    for (unsigned n = task_count / 2; n < task_count; ++n) {
+    for (size_t n = task_count / 2; n < task_count; ++n) {
         TEST_ASSERT_EQUAL(1, tasks[n]->run_call_count());
     }
 
diff --git a/components/ocs_security/isha_engine.h b/components/ocs_security/isha_engine.h
index 6f88459a..982ad11b 100644
--- a/components/ocs_security/isha_engine.h
+++ b/components/ocs_security/isha_engine.h
@@ -5,6 +5,7 @@
 
 #pragma once
 
+#include <cstddef>
 #include <cstdint>
 
 #include "ocs_status/code.h"
@@ -33,7 +34,7 @@ class IShaEngine {
     //!  - @p src should be at least @p size bytes long.
     //!  - @p buf should be large enough to store the result of SHA calculation.
     virtual status::StatusCode
-    generate(uint8_t* buf, const uint8_t* src, unsigned size) = 0;
+    generate(uint8_t* buf, const uint8_t* src, size_t size) = 0;
 };
 
 } // namespace security
diff --git a/components/ocs_security/mbedtls_sha_engine.cpp b/components/ocs_security/mbedtls_sha_engine.cpp
index 1b356a80..7d57e588 100644
--- a/components/ocs_security/mbedtls_sha_engine.cpp
+++ b/components/ocs_security/mbedtls_sha_engine.cpp
@@ -20,7 +20,7 @@ MbedTlsShaEngine::MbedTlsShaEngine(IShaEngine::Algorithm algorithm)
 }
 
 status::StatusCode
-MbedTlsShaEngine::generate(uint8_t* buf, const uint8_t* src, unsigned size) {
+MbedTlsShaEngine::generate(uint8_t* buf, const uint8_t* src, size_t size) {
     int result = 0;
 
     switch (algorithm_) {
diff --git a/components/ocs_security/mbedtls_sha_engine.h b/components/ocs_security/mbedtls_sha_engine.h
index a19d31af..6ba04e74 100644
--- a/components/ocs_security/mbedtls_sha_engine.h
+++ b/components/ocs_security/mbedtls_sha_engine.h
@@ -17,7 +17,7 @@ class MbedTlsShaEngine : public BasicShaEngine, private core::NonCopyable<> {
     explicit MbedTlsShaEngine(IShaEngine::Algorithm algorithm);
 
     //! Generate SHA by using the mbedTLS library.
-    status::StatusCode generate(uint8_t* buf, const uint8_t* src, unsigned size) override;
+    status::StatusCode generate(uint8_t* buf, const uint8_t* src, size_t size) override;
 };
 
 } // namespace security
diff --git a/components/ocs_security/sha_generator.cpp b/components/ocs_security/sha_generator.cpp
index b194a1f0..4677fe90 100644
--- a/components/ocs_security/sha_generator.cpp
+++ b/components/ocs_security/sha_generator.cpp
@@ -18,8 +18,8 @@ const ShaGenerator::Data& ShaGenerator::get_sha() const {
     return sha_;
 }
 
-void ShaGenerator::add(const uint8_t* buf, unsigned size) {
-    for (unsigned n = 0; n < size; ++n) {
+void ShaGenerator::add(const uint8_t* buf, size_t size) {
+    for (size_t n = 0; n < size; ++n) {
         src_.push_back(buf[n]);
     }
 }
diff --git a/components/ocs_security/sha_generator.h b/components/ocs_security/sha_generator.h
index 220260a4..0eb09a58 100644
--- a/components/ocs_security/sha_generator.h
+++ b/components/ocs_security/sha_generator.h
@@ -24,7 +24,7 @@ class ShaGenerator : private core::NonCopyable<> {
     const Data& get_sha() const;
 
     //! Add @p size bytes from @p buf to be used during SHA calculation.
-    void add(const uint8_t* buf, unsigned size);
+    void add(const uint8_t* buf, size_t size);
 
     //! Generate SHA based on the underlying data.
     status::StatusCode generate();
diff --git a/components/ocs_security/sha_to_hex_str.cpp b/components/ocs_security/sha_to_hex_str.cpp
index 9ee46d18..5f8a4014 100644
--- a/components/ocs_security/sha_to_hex_str.cpp
+++ b/components/ocs_security/sha_to_hex_str.cpp
@@ -13,12 +13,12 @@
 namespace ocs {
 namespace security {
 
-sha_to_hex_str::sha_to_hex_str(const uint8_t* sha, unsigned size) {
+sha_to_hex_str::sha_to_hex_str(const uint8_t* sha, size_t size) {
     configASSERT(size <= max_hash_length_);
 
     memset(buf_, 0, sizeof(buf_));
 
-    for (unsigned n = 0; n < size; ++n) {
+    for (size_t n = 0; n < size; ++n) {
         sprintf(buf_ + n * 2, "%02X", sha[n]);
     }
 }
diff --git a/components/ocs_security/sha_to_hex_str.h b/components/ocs_security/sha_to_hex_str.h
index 9d2cfeb6..dfd7eda5 100644
--- a/components/ocs_security/sha_to_hex_str.h
+++ b/components/ocs_security/sha_to_hex_str.h
@@ -18,13 +18,13 @@ class sha_to_hex_str : private core::NonCopyable<> {
     //!
     //! @params
     //!  - @p sha - SHA data, @p size bytes long.
-    sha_to_hex_str(const uint8_t* sha, unsigned size);
+    sha_to_hex_str(const uint8_t* sha, size_t size);
 
     //! Return SHA formatted as a hex string.
     const char* c_str() const;
 
 private:
-    static constexpr unsigned max_hash_length_ =
+    static constexpr size_t max_hash_length_ =
         algo::ShaEngineOps::hash_lenght(IShaEngine::Algorithm::SHA512);
 
     char buf_[max_hash_length_ + 1];
diff --git a/components/ocs_sensor/analog_sample_reader.cpp b/components/ocs_sensor/analog_sample_reader.cpp
index 601a38c4..dde321a1 100644
--- a/components/ocs_sensor/analog_sample_reader.cpp
+++ b/components/ocs_sensor/analog_sample_reader.cpp
@@ -40,7 +40,7 @@ status::StatusCode AnalogSampleReader::read(int& raw) {
 
     int total = 0;
 
-    for (unsigned n = 0; n < sample_count; ++n) {
+    for (size_t n = 0; n < sample_count; ++n) {
         int result = 0;
         OCS_STATUS_RETURN_ON_ERROR(reader_.read(result));
 
diff --git a/components/ocs_sensor/bme280/itransceiver.h b/components/ocs_sensor/bme280/itransceiver.h
index ef4ea8a7..a0f440c0 100644
--- a/components/ocs_sensor/bme280/itransceiver.h
+++ b/components/ocs_sensor/bme280/itransceiver.h
@@ -19,11 +19,11 @@ class ITransceiver {
 
     //! Send @p size registers from @p buf start with @p addr.
     virtual status::StatusCode
-    send(const uint8_t* buf, unsigned size, RegisterAddress addr) = 0;
+    send(const uint8_t* buf, size_t size, RegisterAddress addr) = 0;
 
     //! Receive @p size registers to @p buf start with @p addr.
     virtual status::StatusCode
-    receive(uint8_t* buf, unsigned size, RegisterAddress addr) = 0;
+    receive(uint8_t* buf, size_t size, RegisterAddress addr) = 0;
 };
 
 } // namespace bme280
diff --git a/components/ocs_sensor/bme280/sensor.cpp b/components/ocs_sensor/bme280/sensor.cpp
index 3b6882bd..d8ac6265 100644
--- a/components/ocs_sensor/bme280/sensor.cpp
+++ b/components/ocs_sensor/bme280/sensor.cpp
@@ -121,12 +121,12 @@ Sensor::Data Sensor::get_data() const {
 
 void Sensor::estimate_measurement_time_() {
     // Appendix B: measurement time and current calculation, page 51.
-    const unsigned typ_measurement_duration =
+    const size_t typ_measurement_duration =
         std::ceil(1 + (2 * oversampling_to_coef(params_.temperature_oversampling))
                   + ((2 * oversampling_to_coef(params_.pressure_oversampling)) + 0.5)
                   + ((2 * oversampling_to_coef(params_.humidity_oversampling)) + 0.5));
 
-    const unsigned max_measurement_duration = std::ceil(
+    const size_t max_measurement_duration = std::ceil(
         1.25 + (2.3 * oversampling_to_coef(params_.temperature_oversampling))
         + ((2.3 * oversampling_to_coef(params_.pressure_oversampling)) + 0.575)
         + ((2.3 * oversampling_to_coef(params_.humidity_oversampling)) + 0.575));
@@ -242,7 +242,7 @@ status::StatusCode Sensor::read_calibration1_() {
 
 status::StatusCode Sensor::read_calibration2_() {
     // 7 registers.
-    const unsigned calibration_register_count = 0xE7 - 0xE1 + 1;
+    const size_t calibration_register_count = 0xE7 - 0xE1 + 1;
 
     uint8_t recv_buf[calibration_register_count];
     memset(recv_buf, 0, sizeof(recv_buf));
diff --git a/components/ocs_sensor/bme280/spi_transceiver.cpp b/components/ocs_sensor/bme280/spi_transceiver.cpp
index 39f0d0ca..6ad741f2 100644
--- a/components/ocs_sensor/bme280/spi_transceiver.cpp
+++ b/components/ocs_sensor/bme280/spi_transceiver.cpp
@@ -18,16 +18,16 @@ SpiTransceiver::SpiTransceiver(io::spi::ITransceiver& transceiver)
 }
 
 status::StatusCode
-SpiTransceiver::send(const uint8_t* buf, unsigned size, RegisterAddress addr) {
+SpiTransceiver::send(const uint8_t* buf, size_t size, RegisterAddress addr) {
     //! Each register is sent as a pair of bytes: | control byte | data byte |.
     const auto send_buf_size = size * 2;
 
     uint8_t send_buf[send_buf_size];
     memset(send_buf, 0, sizeof(send_buf));
 
-    unsigned pos = 0;
+    size_t pos = 0;
 
-    for (unsigned n = 0; n < send_buf_size;) {
+    for (size_t n = 0; n < send_buf_size;) {
         //! Set the MSB bit to 0 to indicate a write command.
         const uint8_t control_byte = addr & algo::BitOps::umask(7);
         const uint8_t data_byte = buf[pos];
@@ -43,7 +43,7 @@ SpiTransceiver::send(const uint8_t* buf, unsigned size, RegisterAddress addr) {
 }
 
 status::StatusCode
-SpiTransceiver::receive(uint8_t* buf, unsigned size, RegisterAddress addr) {
+SpiTransceiver::receive(uint8_t* buf, size_t size, RegisterAddress addr) {
     //! Dummy bytes are used to clock out the data we want to receive.
     uint8_t send_buf[size + 1];
     memset(send_buf, 0, sizeof(send_buf));
diff --git a/components/ocs_sensor/bme280/spi_transceiver.h b/components/ocs_sensor/bme280/spi_transceiver.h
index 7938b452..e8dd58c0 100644
--- a/components/ocs_sensor/bme280/spi_transceiver.h
+++ b/components/ocs_sensor/bme280/spi_transceiver.h
@@ -23,11 +23,10 @@ class SpiTransceiver : public ITransceiver, private core::NonCopyable<> {
 
     //! Send registers to SPI device.
     status::StatusCode
-    send(const uint8_t* buf, unsigned size, RegisterAddress addr) override;
+    send(const uint8_t* buf, size_t size, RegisterAddress addr) override;
 
     //! Receive registers from SPI device.
-    status::StatusCode
-    receive(uint8_t* buf, unsigned size, RegisterAddress addr) override;
+    status::StatusCode receive(uint8_t* buf, size_t size, RegisterAddress addr) override;
 
 private:
     io::spi::ITransceiver& transceiver_;
diff --git a/components/ocs_sensor/ds18b20/parse_configuration.cpp b/components/ocs_sensor/ds18b20/parse_configuration.cpp
index b2c34725..db537844 100644
--- a/components/ocs_sensor/ds18b20/parse_configuration.cpp
+++ b/components/ocs_sensor/ds18b20/parse_configuration.cpp
@@ -49,7 +49,7 @@ bool parse_serial_number(onewire::SerialNumber& serial_number,
         return false;
     }
 
-    for (unsigned n = 0; n < OCS_ARRAY_SIZE(serial_number); ++n) {
+    for (size_t n = 0; n < OCS_ARRAY_SIZE(serial_number); ++n) {
         const auto str = values[n];
         if (str.size() != strlen("AA")) {
             return false;
diff --git a/components/ocs_sensor/ds18b20/store.cpp b/components/ocs_sensor/ds18b20/store.cpp
index 85bb5627..b113ce76 100644
--- a/components/ocs_sensor/ds18b20/store.cpp
+++ b/components/ocs_sensor/ds18b20/store.cpp
@@ -24,7 +24,7 @@ const char* log_tag = "ds18b20_store";
 
 } // namespace
 
-Store::Store(system::IRtDelayer& delayer, unsigned max_event_count)
+Store::Store(system::IRtDelayer& delayer, size_t max_event_count)
     : max_event_count_(max_event_count)
     , delayer_(delayer) {
     configASSERT(max_event_count_);
@@ -35,7 +35,7 @@ status::StatusCode Store::run() {
         const auto code = node->run();
         if (code != status::StatusCode::OK) {
             ocs_logw(log_tag, "failed to handle events on the bus: gpio=%d code=%s",
-                     static_cast<unsigned>(gpio), status::code_to_str(code));
+                     static_cast<int>(gpio), status::code_to_str(code));
         }
     }
 
@@ -87,7 +87,7 @@ Store::NodePtr Store::add_node_(io::gpio::Gpio gpio, const char* gpio_id) {
 Store::Node::Node(system::IRtDelayer& delayer,
                   io::gpio::Gpio gpio,
                   const char* gpio_id,
-                  unsigned max_event_count)
+                  size_t max_event_count)
     : func_scheduler_(max_event_count) {
     gpio_.reset(new (std::nothrow) io::gpio::DefaultGpio(gpio_id, gpio));
     configASSERT(gpio_);
diff --git a/components/ocs_sensor/ds18b20/store.h b/components/ocs_sensor/ds18b20/store.h
index 077f2e5f..b9dc2abc 100644
--- a/components/ocs_sensor/ds18b20/store.h
+++ b/components/ocs_sensor/ds18b20/store.h
@@ -34,7 +34,7 @@ class Store : public scheduler::ITask, private core::NonCopyable<> {
     //!  - @p max_event_count - maximum number of asynchronous events that can be
     //!    scheduled per 1-Wire bus. If the value is too small and the run() is called
     //!    rarely, it's possible to miss some events.
-    Store(system::IRtDelayer& delayer, unsigned max_event_count);
+    Store(system::IRtDelayer& delayer, size_t max_event_count);
 
     //! Handle asynchronous events on the 1-wire buses.
     status::StatusCode run() override;
@@ -60,7 +60,7 @@ class Store : public scheduler::ITask, private core::NonCopyable<> {
         Node(system::IRtDelayer& delayer,
              io::gpio::Gpio gpio,
              const char* gpio_id,
-             unsigned max_event_count);
+             size_t max_event_count);
 
         //! Handle operations on the 1-Wire bus.
         status::StatusCode run() override;
@@ -86,7 +86,7 @@ class Store : public scheduler::ITask, private core::NonCopyable<> {
     NodePtr get_node_(io::gpio::Gpio gpio);
     NodePtr add_node_(io::gpio::Gpio gpio, const char* gpio_id);
 
-    const unsigned max_event_count_ { 0 };
+    const size_t max_event_count_ { 0 };
 
     system::IRtDelayer& delayer_;
 
diff --git a/components/ocs_sensor/sht4x/sensor.h b/components/ocs_sensor/sht4x/sensor.h
index 2decf4a0..a5eb43e9 100644
--- a/components/ocs_sensor/sht4x/sensor.h
+++ b/components/ocs_sensor/sht4x/sensor.h
@@ -31,7 +31,7 @@ class Sensor : public scheduler::ITask, private core::NonCopyable<> {
     struct Data {
         double humidity { 0.0 };
         double temperature { 0.0 };
-        unsigned heating_count { 0 };
+        size_t heating_count { 0 };
     };
 
     enum class Command {
@@ -136,7 +136,7 @@ class Sensor : public scheduler::ITask, private core::NonCopyable<> {
     storage::IStorage& storage_;
 
     TickType_t heating_delay_ { 0 };
-    unsigned heating_count_ { 0 };
+    size_t heating_count_ { 0 };
 
     bool initialized_ { false };
     SerialNumber serial_number_ { 0 };
diff --git a/components/ocs_sensor/sht4x/serial_number_to_str.h b/components/ocs_sensor/sht4x/serial_number_to_str.h
index a05bb793..9e834415 100644
--- a/components/ocs_sensor/sht4x/serial_number_to_str.h
+++ b/components/ocs_sensor/sht4x/serial_number_to_str.h
@@ -17,7 +17,7 @@ namespace sht4x {
 //! Format sensor serial number to string.
 class serial_number_to_str : private core::NonCopyable<> {
 public:
-    static constexpr unsigned str_length = strlen("AA:BB:CC:DD");
+    static constexpr size_t str_length = strlen("AA:BB:CC:DD");
 
     //! Initialize.
     serial_number_to_str(const SerialNumber& serial_number);
diff --git a/components/ocs_sensor/test/soil/test_analog_sensor.cpp b/components/ocs_sensor/test/soil/test_analog_sensor.cpp
index 33951910..e9518d4c 100644
--- a/components/ocs_sensor/test/soil/test_analog_sensor.cpp
+++ b/components/ocs_sensor/test/soil/test_analog_sensor.cpp
@@ -158,7 +158,7 @@ TEST_CASE("Soil analog sensor: validate each status",
     const uint16_t def_max = 26;
     const char* id = "test";
 
-    const unsigned status_interval =
+    const uint16_t status_interval =
         (def_max - def_min) / AnalogSensor::get_status_count();
 
     const system::Time resolution = system::Duration::second;
@@ -341,7 +341,7 @@ TEST_CASE("Soil analog sensor: read initial status from storage",
     const char* id = "test";
     const system::Time resolution = system::Duration::second;
 
-    const unsigned status_interval =
+    const uint16_t status_interval =
         (def_max - def_min) / AnalogSensor::get_status_count();
 
     test::MemoryStorage config_storage;
@@ -422,7 +422,7 @@ TEST_CASE("Soil analog sensor: ignore changes close to the threshold: valid stat
     const uint16_t range = def_max - def_min;
     TEST_ASSERT_TRUE((range % AnalogSensor::get_status_count()) == 0);
 
-    const unsigned status_interval = range / AnalogSensor::get_status_count();
+    const uint16_t status_interval = range / AnalogSensor::get_status_count();
     const uint8_t status_threshold = 49;
     const double moisture_per_off = static_cast<double>(1) / range;
 
@@ -550,7 +550,7 @@ TEST_CASE("Soil analog sensor: ignore changes close to the threshold: invalid st
     const uint16_t range = def_max - def_min;
     TEST_ASSERT_TRUE((range % AnalogSensor::get_status_count()) == 0);
 
-    const unsigned status_interval = range / AnalogSensor::get_status_count();
+    const uint16_t status_interval = range / AnalogSensor::get_status_count();
     const uint8_t status_threshold = 49;
     const double moisture_per_off = static_cast<double>(1) / range;
 
diff --git a/components/ocs_sensor/test/test_analog_sample_reader.cpp b/components/ocs_sensor/test/test_analog_sample_reader.cpp
index 9b95ac10..1fae0e67 100644
--- a/components/ocs_sensor/test/test_analog_sample_reader.cpp
+++ b/components/ocs_sensor/test/test_analog_sample_reader.cpp
@@ -32,7 +32,7 @@ Samples generate_samples(const AnalogConfig& config) {
 
     Samples samples;
 
-    for (unsigned n = 0; n < config.get_sample_count(); ++n) {
+    for (size_t n = 0; n < config.get_sample_count(); ++n) {
         samples.push_back(random(static_cast<uint16_t>(0), max_value));
     }
 
diff --git a/components/ocs_storage/target_esp32/nvs_storage.cpp b/components/ocs_storage/target_esp32/nvs_storage.cpp
index 2fcdbc23..9c55a6ef 100644
--- a/components/ocs_storage/target_esp32/nvs_storage.cpp
+++ b/components/ocs_storage/target_esp32/nvs_storage.cpp
@@ -24,7 +24,7 @@ NvsStorage::NvsStorage(const char* ns) {
     configASSERT(strlen(ns) <= max_namespace_len);
 
     memset(ns_, 0, sizeof(ns_));
-    strncpy(ns_, ns, std::min(max_namespace_len, strlen(ns)));
+    strncpy(ns_, ns, std::min(static_cast<size_t>(max_namespace_len), strlen(ns)));
 }
 
 status::StatusCode NvsStorage::probe(const char* key, size_t& size) {
diff --git a/components/ocs_storage/target_esp32/nvs_storage.h b/components/ocs_storage/target_esp32/nvs_storage.h
index 397594ad..68807381 100644
--- a/components/ocs_storage/target_esp32/nvs_storage.h
+++ b/components/ocs_storage/target_esp32/nvs_storage.h
@@ -19,7 +19,7 @@ namespace storage {
 class NvsStorage : public IStorage, private core::NonCopyable<> {
 public:
     //! Maximum number of symbols for the storage namespace, without NULL character.
-    static constexpr unsigned max_namespace_len = NVS_KEY_NAME_MAX_SIZE - 1;
+    static constexpr uint8_t max_namespace_len = NVS_KEY_NAME_MAX_SIZE - 1;
 
     //! Initialize.
     //!
diff --git a/components/ocs_storage/test/target_esp32/test_nvs_storage.cpp b/components/ocs_storage/test/target_esp32/test_nvs_storage.cpp
index 02fa6de1..d17ea8a0 100644
--- a/components/ocs_storage/test/target_esp32/test_nvs_storage.cpp
+++ b/components/ocs_storage/test/target_esp32/test_nvs_storage.cpp
@@ -18,8 +18,8 @@ TEST_CASE("NVS storage: write-read-erase", "[ocs_storage], [nvs_storage]") {
     FlashInitializer initializer;
 
     const char* id = "foo";
-    const unsigned write_value = 42;
-    unsigned read_value = 0;
+    const size_t write_value = 42;
+    size_t read_value = 0;
 
     NvsStorage storage("tests");
 
@@ -44,7 +44,7 @@ TEST_CASE("NVS storage: read: no data", "[ocs_storage], [nvs_storage]") {
     FlashInitializer initializer;
 
     const char* id = "foo";
-    unsigned value = 0;
+    size_t value = 0;
 
     NvsStorage storage("tests");
     TEST_ASSERT_EQUAL(status::StatusCode::NoData,
@@ -97,9 +97,9 @@ TEST_CASE("NVS storage: overwrite key", "[ocs_storage], [nvs_storage]") {
     FlashInitializer initializer;
 
     const char* id = "overwrite";
-    const unsigned initial_value = 10;
-    const unsigned updated_value = 20;
-    unsigned read_value = 0;
+    const size_t initial_value = 10;
+    const size_t updated_value = 20;
+    size_t read_value = 0;
 
     NvsStorage storage("tests");
 
diff --git a/components/ocs_system/test/target_esp32/test_rt_delayer.cpp b/components/ocs_system/test/target_esp32/test_rt_delayer.cpp
index 8dcccd59..68e15dcc 100644
--- a/components/ocs_system/test/target_esp32/test_rt_delayer.cpp
+++ b/components/ocs_system/test/target_esp32/test_rt_delayer.cpp
@@ -13,7 +13,7 @@ namespace system {
 TEST_CASE("Rt delayer: delay", "[ocs_system], [rt_delayer]") {
     RtDelayer delayer;
 
-    for (unsigned n = 0; n < 10; ++n) {
+    for (size_t n = 0; n < 10; ++n) {
         delayer.delay(system::Duration::microsecond * 100);
     }
 }
diff --git a/components/ocs_system/test/test_fanout_suspender.cpp b/components/ocs_system/test/test_fanout_suspender.cpp
index 9fac7da1..13c7d21c 100644
--- a/components/ocs_system/test/test_fanout_suspender.cpp
+++ b/components/ocs_system/test/test_fanout_suspender.cpp
@@ -31,8 +31,8 @@ class TestHandler : public ISuspendHandler {
         return resume_code_;
     }
 
-    unsigned suspend_count { 0 };
-    unsigned resume_count { 0 };
+    size_t suspend_count { 0 };
+    size_t resume_count { 0 };
 
 private:
     status::StatusCode suspend_code_ { status::StatusCode::OK };
diff --git a/components/ocs_system/time.h b/components/ocs_system/time.h
index 37b557b3..1ce9f7b4 100644
--- a/components/ocs_system/time.h
+++ b/components/ocs_system/time.h
@@ -22,7 +22,7 @@ using Time = int64_t;
 //!
 //! To convert an integer number of units to a Duration, multiply:
 //!
-//! const unsigned seconds = 10;
+//! const size_t seconds = 10;
 //! print(seconds * Duration::second) // prints 10 * 1000 * 1000
 struct Duration {
     //! One microsecond represented in microseconds.
diff --git a/components/ocs_test/test_gpio.h b/components/ocs_test/test_gpio.h
index f93b322b..e7efc33c 100644
--- a/components/ocs_test/test_gpio.h
+++ b/components/ocs_test/test_gpio.h
@@ -5,6 +5,8 @@
 
 #pragma once
 
+#include <cstddef>
+
 #include "ocs_core/noncopyable.h"
 #include "ocs_io/gpio/igpio.h"
 
@@ -23,9 +25,9 @@ class TestGpio : public io::gpio::IGpio, private core::NonCopyable<> {
     status::StatusCode turn_off() override;
     status::StatusCode set_direction(IGpio::Direction direction) override;
 
-    unsigned flip_call_count { 0 };
-    unsigned turn_on_call_count { 0 };
-    unsigned turn_off_call_count { 0 };
+    size_t flip_call_count { 0 };
+    size_t turn_on_call_count { 0 };
+    size_t turn_off_call_count { 0 };
     IGpio::Direction direction { IGpio::Direction::Output };
 
 private:
diff --git a/components/ocs_test/test_task.cpp b/components/ocs_test/test_task.cpp
index 60516724..ec9cadac 100644
--- a/components/ocs_test/test_task.cpp
+++ b/components/ocs_test/test_task.cpp
@@ -32,7 +32,7 @@ bool TestTask::was_run_called() const {
     return run_called_;
 }
 
-unsigned TestTask::run_call_count() const {
+size_t TestTask::run_call_count() const {
     core::LockGuard lock(mu_);
 
     return run_call_count_;
diff --git a/components/ocs_test/test_task.h b/components/ocs_test/test_task.h
index 2c99c499..ca483c62 100644
--- a/components/ocs_test/test_task.h
+++ b/components/ocs_test/test_task.h
@@ -20,7 +20,7 @@ class TestTask : public scheduler::ITask, private core::NonCopyable<> {
     status::StatusCode run() override;
 
     bool was_run_called() const;
-    unsigned run_call_count() const;
+    size_t run_call_count() const;
 
     //! Reset to initial state.
     void reset(status::StatusCode code);
@@ -34,7 +34,7 @@ class TestTask : public scheduler::ITask, private core::NonCopyable<> {
 
     status::StatusCode code_ { status::StatusCode::OK };
     bool run_called_ { false };
-    unsigned run_call_count_ { 0 };
+    size_t run_call_count_ { 0 };
 };
 
 } // namespace test
diff --git a/components/ocs_test/test_timer.h b/components/ocs_test/test_timer.h
index e7a81713..2ee41e38 100644
--- a/components/ocs_test/test_timer.h
+++ b/components/ocs_test/test_timer.h
@@ -5,6 +5,8 @@
 
 #pragma once
 
+#include <cstddef>
+
 #include "ocs_core/noncopyable.h"
 #include "ocs_system/itimer.h"
 
@@ -18,8 +20,8 @@ class TestTimer : public system::ITimer, private core::NonCopyable<> {
     status::StatusCode start() override;
     status::StatusCode stop() override;
 
-    unsigned start_call_count { 0 };
-    unsigned stop_call_count { 0 };
+    size_t start_call_count { 0 };
+    size_t stop_call_count { 0 };
 
 private:
     status::StatusCode code_ { status::StatusCode::OK };
diff --git a/projects/ds18b20-verifier/main/main.cpp b/projects/ds18b20-verifier/main/main.cpp
index e2cba73d..be90d5a2 100644
--- a/projects/ds18b20-verifier/main/main.cpp
+++ b/projects/ds18b20-verifier/main/main.cpp
@@ -31,7 +31,7 @@ const char* log_tag = "ds18b20_verifier";
 
 struct VerifyParams {
     io::gpio::Gpio gpio { static_cast<io::gpio::Gpio>(-1) };
-    unsigned total_attempts { 0 };
+    size_t total_attempts { 0 };
     TickType_t delay { pdMS_TO_TICKS(0) };
 };
 
@@ -107,9 +107,9 @@ void read_device(onewire::Bus& bus,
                  const onewire::RomCode& rom_code,
                  cJSON* json,
                  VerifyParams verify_params) {
-    unsigned failed_attempts = 0;
+    size_t failed_attempts = 0;
 
-    for (unsigned n = 0; n < verify_params.total_attempts; ++n) {
+    for (size_t n = 0; n < verify_params.total_attempts; ++n) {
         const auto code = read_temperature(bus, rom_code);
         if (code != status::StatusCode::OK) {
             ++failed_attempts;
diff --git a/projects/sht4x-verifier/main/main.cpp b/projects/sht4x-verifier/main/main.cpp
index 9fdc32b0..cbe1e4f3 100644
--- a/projects/sht4x-verifier/main/main.cpp
+++ b/projects/sht4x-verifier/main/main.cpp
@@ -71,10 +71,10 @@ extern "C" void app_main(void) {
         ocs_logw(log_tag, "failed to reset sensor: %s", status::code_to_str(code));
     }
 
-    const unsigned total_attempts = CONFIG_OCS_TOOLS_SHT4x_VERIFIER_TOTAL_ATTEMPTS;
-    unsigned failed_attempts = 0;
+    const size_t total_attempts = CONFIG_OCS_TOOLS_SHT4x_VERIFIER_TOTAL_ATTEMPTS;
+    size_t failed_attempts = 0;
 
-    for (unsigned n = 0; n < total_attempts; ++n) {
+    for (size_t n = 0; n < total_attempts; ++n) {
         const auto code = sensor->run();
         if (code != status::StatusCode::OK) {
             ++failed_attempts;