diff --git a/src/realloc.cpp b/src/realloc.cpp
index c580de5..7820244 100644
--- a/src/realloc.cpp
+++ b/src/realloc.cpp
@@ -5,9 +5,26 @@ namespace mem
 
 void* realloc(void* ptr, size_t new_size)
 {
-    (void)ptr;
-    (void)new_size;
-    return nullptr;
+    if (ptr == nullptr)
+    {
+        return malloc(new_size);
+    }
+
+    if (new_size == 0)
+    {
+        free(ptr);
+        return nullptr;
+    }
+
+    void* new_ptr = malloc(new_size);
+    if (new_ptr == nullptr)
+    {
+        return nullptr;
+    }
+
+    free(ptr);
+
+    return new_ptr;
 }
 
 } // namespace mem
diff --git a/tests/unit/test_realloc.cpp b/tests/unit/test_realloc.cpp
new file mode 100644
index 0000000..dce71a6
--- /dev/null
+++ b/tests/unit/test_realloc.cpp
@@ -0,0 +1,10 @@
+#include "malloc_from_scratch/memory_allocator.h"
+#include "test_utils.h"
+
+int main()
+{
+    void* null_ptr = mem::realloc(nullptr, 64);
+    ASSERT_NOT_NULL(null_ptr);
+
+    TEST_PASS();
+}