diff --git a/.github/workflows/cmake-multi-platform.yml b/.github/workflows/cmake-multi-platform.yml
index d3aff61..905ff0b 100644
--- a/.github/workflows/cmake-multi-platform.yml
+++ b/.github/workflows/cmake-multi-platform.yml
@@ -12,6 +12,7 @@ on:
 
 jobs:
   build:
+    name: Build (Bundled ${{ matrix.bundled_protobuf }}, ${{ matrix.build_type }})
     runs-on: ${{ matrix.os }}
 
     strategy:
@@ -28,16 +29,26 @@ jobs:
         os: [ubuntu-24.04]
         build_type: [Release, Debug]
         c_compiler: [clang]
-        include:
-          - os: ubuntu-24.04
-            c_compiler: clang
-            cpp_compiler: clang++
+        cpp_compiler: [clang++]
+        bundled_protobuf: ['ON', 'OFF']
 
     steps:
     - uses: actions/checkout@v3
 
     - name: Install Deps
-      run: sudo apt install -y liblzma-dev ninja-build
+      run: |
+        ubuntu_packages=(
+          liblzma-dev
+          ninja-build
+        )
+        if [[ ${{ matrix.bundled_protobuf }} == OFF ]]; then
+          ubuntu_packages+=(
+            libprotobuf-dev
+            protobuf-compiler
+          )
+        fi
+        set -x
+        sudo apt install -y "${ubuntu_packages[@]}"
 
     - name: Set reusable strings
       # Turn repeated input strings (such as the build output directory) into step outputs. These step outputs can be used throughout the workflow file.
@@ -56,7 +67,7 @@ jobs:
         -DCMAKE_C_COMPILER=${{ matrix.c_compiler }}
         -DCMAKE_C_FLAGS='-Werror'
         -DCMAKE_BUILD_TYPE=${{ matrix.build_type }}
-        -DLIB_PROTO_MUTATOR_DOWNLOAD_PROTOBUF=ON
+        -DLIB_PROTO_MUTATOR_DOWNLOAD_PROTOBUF=${{ matrix.bundled_protobuf }}
         -GNinja
         -S ${{ github.workspace }}
 
diff --git a/examples/libfuzzer/libfuzzer_bin_example.cc b/examples/libfuzzer/libfuzzer_bin_example.cc
index 62bb45a..cd31aad 100644
--- a/examples/libfuzzer/libfuzzer_bin_example.cc
+++ b/examples/libfuzzer/libfuzzer_bin_example.cc
@@ -55,7 +55,7 @@ DEFINE_BINARY_PROTO_FUZZER(const libfuzzer_example::Msg& message) {
       !std::isnan(message.optional_float()) &&
       std::fabs(message.optional_float()) > 1000 &&
       message.any().UnpackTo(&file) && !file.name().empty()) {
-    std::cerr << protobuf_mutator::protobuf::ShortFormat(message) << "\n";
+    std::cerr << message.DebugString() << "\n";
     abort();
   }
 }
diff --git a/examples/libfuzzer/libfuzzer_example.cc b/examples/libfuzzer/libfuzzer_example.cc
index a7b9ba5..2e6e887 100644
--- a/examples/libfuzzer/libfuzzer_example.cc
+++ b/examples/libfuzzer/libfuzzer_example.cc
@@ -55,7 +55,7 @@ DEFINE_PROTO_FUZZER(const libfuzzer_example::Msg& message) {
       !std::isnan(message.optional_float()) &&
       std::fabs(message.optional_float()) > 1000 &&
       message.any().UnpackTo(&file) && !file.name().empty()) {
-    std::cerr << protobuf_mutator::protobuf::ShortFormat(message) << "\n";
+    std::cerr << message.DebugString() << "\n";
     abort();
   }
 }
diff --git a/src/field_instance.h b/src/field_instance.h
index 823d19b..e05d8e9 100644
--- a/src/field_instance.h
+++ b/src/field_instance.h
@@ -190,14 +190,22 @@ class ConstFieldInstance {
     return descriptor_->message_type();
   }
 
-  bool EnforceUtf8() const { return descriptor_->requires_utf8_validation(); }
+  bool EnforceUtf8() const {
+#if PROTOBUF_VERSION >= 4022000  // v3(!).22.0 (commit d85c9944c55fb38f4eae149979a0f680ea125ecb) for requires_utf8_validation
+    return descriptor_->requires_utf8_validation();
+#else
+    return descriptor_->type() == protobuf::FieldDescriptor::TYPE_STRING &&
+           descriptor()->file()->syntax() ==
+               protobuf::FileDescriptor::SYNTAX_PROTO3;
+#endif
+  }
 
   const protobuf::FieldDescriptor* descriptor() const { return descriptor_; }
 
   std::string DebugString() const {
     std::string s = descriptor_->DebugString();
     if (is_repeated()) s += "[" + std::to_string(index_) + "]";
-    return s + " of\n" + protobuf::ShortFormat(*message_);
+    return s + " of\n" + message_->DebugString();
   }
 
  protected:
diff --git a/src/mutator.cc b/src/mutator.cc
index 191204e..ee2f213 100644
--- a/src/mutator.cc
+++ b/src/mutator.cc
@@ -801,7 +801,7 @@ std::string Mutator::MutateUtf8String(const std::string& value,
 
 bool Mutator::IsInitialized(const Message& message) const {
   if (!keep_initialized_ || message.IsInitialized()) return true;
-  std::cerr << "Uninitialized: " << protobuf::ShortFormat(message) << "\n";
+  std::cerr << "Uninitialized: " << message.DebugString() << "\n";
   return false;
 }
 
diff --git a/src/mutator_test.cc b/src/mutator_test.cc
index 8cd5013..e534e1e 100644
--- a/src/mutator_test.cc
+++ b/src/mutator_test.cc
@@ -410,8 +410,8 @@ bool Mutate(const protobuf::Message& from, const protobuf::Message& to,
   }
 
   ADD_FAILURE() << "Failed to get from:\n"
-                << protobuf::ShortFormat(from) << "\nto:\n"
-                << protobuf::ShortFormat(to);
+                << from.DebugString() << "\nto:\n"
+                << to.DebugString();
   return false;
 }