diff --git a/.github/workflows/gha.yml b/.github/workflows/gha.yml
index d4b88b8b..bcf43070 100644
--- a/.github/workflows/gha.yml
+++ b/.github/workflows/gha.yml
@@ -315,6 +315,6 @@ jobs:
         echo $env:BOOST_ROOT
         $env:DBOOST_ROOT="$env:Boost_ROOT"
         Start-Process cmake -ArgumentList "-DBOOST_ROOT=""$env:BOOST_ROOT"" $CPP11 $BOOST $X3_PARSE -DGTEST_LIBRARY=""$CUR\googletest-release-1.7.0\build\Release\gtest.lib"" -DGTEST_MAIN_LIBRARY=""$CUR\googletest-release-1.7.0\build\Release\gtest_main.lib"" -DGTEST_INCLUDE_DIR=""$CUR\googletest-release-1.7.0\include"" -DZLIB_LIBRARY=""$CUR\zlib-1.2.11\build\Release\zlib.lib"" -DZLIB_INCLUDE_DIR=""$CUR\zlib-1.2.11"" -DCMAKE_CXX_FLAGS=""/D_VARIADIC_MAX=10 /EHsc /D_SILENCE_TR1_NAMESPACE_DEPRECATION_WARNING"" .." -NoNewWindow -Wait
-        cmake --build . --config Release
+        cmake --build . --config Release -v
         $env:PATH="$env:PATH;$CUR\googletest-release-1.7.0\build\Release;$CUR\zlib-1.2.11\build\Release;$CUR\build\release"
         ctest -V
diff --git a/CMakeLists.txt b/CMakeLists.txt
index e16d63b8..d66a5112 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -313,6 +313,14 @@ IF ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
     ENDIF ()
 ENDIF ()
 
+IF ("${CMAKE_C_COMPILER_ID}" STREQUAL "MSVC")
+    IF (CMAKE_C_FLAGS MATCHES "/W[0-4]")
+        STRING(REGEX REPLACE "/W[0-4]" "/W3 /WX" CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")
+    ELSE ()
+        SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /W3 /WX")
+    ENDIF ()
+ENDIF ()
+
 IF ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC90" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC10")
     SET_SOURCE_FILES_PROPERTIES(${msgpackc_SOURCES} PROPERTIES LANGUAGE CXX)
 ENDIF ()
diff --git a/appveyor.yml b/appveyor.yml
index 8775c0a1..29d75339 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -55,7 +55,7 @@ build_script:
 - md build
 - cd build
 - cmake -G %msvc% %cpp11% %boost% %x3_parse% -DGTEST_LIBRARY=%APPVEYOR_BUILD_FOLDER%\googletest-release-1.7.0\build\Release\gtest.lib -DGTEST_MAIN_LIBRARY=%APPVEYOR_BUILD_FOLDER%\googletest-release-1.7.0\build\Release\gtest_main.lib -DGTEST_INCLUDE_DIR=%APPVEYOR_BUILD_FOLDER%\googletest-release-1.7.0\include -DZLIB_LIBRARY=%APPVEYOR_BUILD_FOLDER%\zlib-1.2.11\build\Release\zlib.lib -DZLIB_INCLUDE_DIR=%APPVEYOR_BUILD_FOLDER%\zlib-1.2.11 -DCMAKE_CXX_FLAGS='"/D_VARIADIC_MAX=10 /EHsc"' ..
-- cmake --build . --config Release
+- cmake --build . --config Release -v
 
 test_script:
 - set PATH=%PATH%;%APPVEYOR_BUILD_FOLDER%\googletest-release-1.7.0\build\Release;%APPVEYOR_BUILD_FOLDER%\zlib-1.2.11\build\Release;%APPVEYOR_BUILD_FOLDER%\build\release
diff --git a/example/c/CMakeLists.txt b/example/c/CMakeLists.txt
index 9333cb54..ca2b7bb0 100644
--- a/example/c/CMakeLists.txt
+++ b/example/c/CMakeLists.txt
@@ -15,19 +15,19 @@ FOREACH (source_file ${exec_PROGRAMS})
     TARGET_LINK_LIBRARIES (${source_file_we}
         msgpackc
     )
-    IF ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
+    IF ("${CMAKE_C_COMPILER_ID}" STREQUAL "Clang" OR "${CMAKE_C_COMPILER_ID}" STREQUAL "GNU")
         SET_PROPERTY (TARGET ${source_file_we} APPEND_STRING PROPERTY COMPILE_FLAGS " -Wall -Wextra")
     ENDIF ()
 
-    IF ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
+    IF ("${CMAKE_C_COMPILER_ID}" STREQUAL "Clang")
         SET_PROPERTY (TARGET ${source_file_we} APPEND_STRING PROPERTY COMPILE_FLAGS " -Wno-mismatched-tags")
     ENDIF ()
 
-    IF ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
-        IF (CMAKE_CXX_FLAGS MATCHES "/W[0-4]")
-            STRING(REGEX REPLACE "/W[0-4]" "/W3 /WX" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+    IF ("${CMAKE_C_COMPILER_ID}" STREQUAL "MSVC")
+        IF (CMAKE_C_FLAGS MATCHES "/W[0-4]")
+            STRING(REGEX REPLACE "/W[0-4]" "/W3 /WX" CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")
         ELSE ()
-            SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /W3 /WX")
+            SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /W3 /WX")
         ENDIF ()
     ENDIF ()
 ENDFOREACH ()
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 2cbc2d6e..56c6b7aa 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -96,10 +96,10 @@ FOREACH (source_file ${check_PROGRAMS})
     ENDIF ()
 
     IF ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
-        IF (CMAKE_CXX_FLAGS MATCHES "/W[0-4] /WX")
+        IF (CMAKE_CXX_FLAGS MATCHES "/W[0-4]")
             STRING(REGEX REPLACE "/W[0-4]" "/W3 /WX" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
         ELSE ()
-            SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /W3")
+            SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /W3 /WX")
         ENDIF ()
     ENDIF ()
 ENDFOREACH ()
diff --git a/test/array_ref.cpp b/test/array_ref.cpp
index b45356ac..dc231768 100644
--- a/test/array_ref.cpp
+++ b/test/array_ref.cpp
@@ -3,12 +3,16 @@
 #include <string>
 #include <sstream>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
diff --git a/test/boost_fusion.cpp b/test/boost_fusion.cpp
index 3b003515..e4209a69 100644
--- a/test/boost_fusion.cpp
+++ b/test/boost_fusion.cpp
@@ -3,12 +3,16 @@
 #include <iterator>
 #include <cmath>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
diff --git a/test/boost_optional.cpp b/test/boost_optional.cpp
index 9d540252..eb36335e 100644
--- a/test/boost_optional.cpp
+++ b/test/boost_optional.cpp
@@ -2,12 +2,16 @@
 #include <sstream>
 #include <iterator>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 
 #ifdef HAVE_CONFIG_H
diff --git a/test/boost_string_ref.cpp b/test/boost_string_ref.cpp
index b6968975..be91f612 100644
--- a/test/boost_string_ref.cpp
+++ b/test/boost_string_ref.cpp
@@ -2,13 +2,16 @@
 #include <sstream>
 #include <iterator>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
-
+#endif //defined(__GNUC__)
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
diff --git a/test/boost_string_view.cpp b/test/boost_string_view.cpp
index 97f55f1e..b5a67fe1 100644
--- a/test/boost_string_view.cpp
+++ b/test/boost_string_view.cpp
@@ -2,12 +2,16 @@
 #include <sstream>
 #include <iterator>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
diff --git a/test/boost_variant.cpp b/test/boost_variant.cpp
index 3c8d0cf3..6846855e 100644
--- a/test/boost_variant.cpp
+++ b/test/boost_variant.cpp
@@ -3,12 +3,16 @@
 #include <sstream>
 #include <iterator>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
diff --git a/test/buffer.cpp b/test/buffer.cpp
index 18cc7aac..4e099e22 100644
--- a/test/buffer.cpp
+++ b/test/buffer.cpp
@@ -4,12 +4,16 @@
 #include <msgpack/zbuffer.hpp>
 #include <msgpack/zbuffer.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #include <string.h>
 
diff --git a/test/carray.cpp b/test/carray.cpp
index 99bb8b04..a7eda14c 100644
--- a/test/carray.cpp
+++ b/test/carray.cpp
@@ -1,11 +1,15 @@
 #include <msgpack.hpp>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #include <sstream>
 
diff --git a/test/cases.cpp b/test/cases.cpp
index c0ae207e..8f4f4feb 100644
--- a/test/cases.cpp
+++ b/test/cases.cpp
@@ -1,12 +1,16 @@
 #include <msgpack.hpp>
 #include <fstream>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 static void feed_file(msgpack::unpacker& pac, const char* path)
 {
diff --git a/test/convert.cpp b/test/convert.cpp
index 9e1de4a7..845e9346 100644
--- a/test/convert.cpp
+++ b/test/convert.cpp
@@ -1,11 +1,15 @@
 #include <msgpack.hpp>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 class enum_member {
 public:
diff --git a/test/fixint.cpp b/test/fixint.cpp
index 4aa951f7..5f8214c9 100644
--- a/test/fixint.cpp
+++ b/test/fixint.cpp
@@ -1,11 +1,15 @@
 #include <msgpack.hpp>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 template <typename T>
 void check_size(size_t size) {
diff --git a/test/fixint_c.cpp b/test/fixint_c.cpp
index 2060c90f..3f9aa351 100644
--- a/test/fixint_c.cpp
+++ b/test/fixint_c.cpp
@@ -1,11 +1,15 @@
 #include <msgpack.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 TEST(fixint, size)
 {
diff --git a/test/fuzz_unpack_pack_fuzzer_cpp11.cpp b/test/fuzz_unpack_pack_fuzzer_cpp11.cpp
index 956a7f62..de2105f4 100644
--- a/test/fuzz_unpack_pack_fuzzer_cpp11.cpp
+++ b/test/fuzz_unpack_pack_fuzzer_cpp11.cpp
@@ -1,9 +1,13 @@
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #include "../fuzz/unpack_pack_fuzzer.cpp"
 
diff --git a/test/iterator_cpp11.cpp b/test/iterator_cpp11.cpp
index df5a5200..967cede2 100644
--- a/test/iterator_cpp11.cpp
+++ b/test/iterator_cpp11.cpp
@@ -1,11 +1,15 @@
 #include <msgpack.hpp>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
diff --git a/test/json.cpp b/test/json.cpp
index 33d00cae..328cc82f 100644
--- a/test/json.cpp
+++ b/test/json.cpp
@@ -2,12 +2,16 @@
 #include <fstream>
 #include <sstream>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 TEST(json, basic_elements)
 {
diff --git a/test/limit.cpp b/test/limit.cpp
index a5cbad7e..f5cfe149 100644
--- a/test/limit.cpp
+++ b/test/limit.cpp
@@ -1,11 +1,15 @@
 #include <msgpack.hpp>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #include <sstream>
 
diff --git a/test/msgpack_basic.cpp b/test/msgpack_basic.cpp
index 48968a1f..32e9c493 100644
--- a/test/msgpack_basic.cpp
+++ b/test/msgpack_basic.cpp
@@ -9,12 +9,16 @@
 #include <list>
 #include <limits>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #if defined(_MSC_VER) || defined(__MINGW32__)
 #define msgpack_rand() ((double)rand() / RAND_MAX)
diff --git a/test/msgpack_c.cpp b/test/msgpack_c.cpp
index 4c94054f..7b76a793 100644
--- a/test/msgpack_c.cpp
+++ b/test/msgpack_c.cpp
@@ -4,12 +4,16 @@
 #include <vector>
 #include <limits>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #if defined(_MSC_VER) || defined(__MINGW32__)
 #define msgpack_rand() ((double)rand() / RAND_MAX)
diff --git a/test/msgpack_container.cpp b/test/msgpack_container.cpp
index e2c59609..0295bbd1 100644
--- a/test/msgpack_container.cpp
+++ b/test/msgpack_container.cpp
@@ -12,12 +12,16 @@
 
 #include "test_allocator.hpp"
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
diff --git a/test/msgpack_cpp11.cpp b/test/msgpack_cpp11.cpp
index d9ea82ed..d69af910 100644
--- a/test/msgpack_cpp11.cpp
+++ b/test/msgpack_cpp11.cpp
@@ -1,11 +1,15 @@
 #include <msgpack.hpp>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
@@ -883,7 +887,7 @@ TEST(MSGPACK_CHRONO, system_clock_32)
     msgpack::sbuffer sbuf;
     msgpack::pack(sbuf, val1);
     char packed[] = {
-        static_cast<char>(0xd6),
+        static_cast<char>(0xd6u),
         static_cast<char>(-1),
         static_cast<char>(0x12),
         static_cast<char>(0x34),
@@ -908,12 +912,12 @@ TEST(MSGPACK_CHRONO, system_clock_32_max)
     msgpack::sbuffer sbuf;
     msgpack::pack(sbuf, val1);
     char packed[] = {
-        static_cast<char>(0xd6),
+        static_cast<char>(0xd6u),
         static_cast<char>(-1),
-        static_cast<char>(0xff),
-        static_cast<char>(0xff),
-        static_cast<char>(0xff),
-        static_cast<char>(0xff)
+        static_cast<char>(0xffu),
+        static_cast<char>(0xffu),
+        static_cast<char>(0xffu),
+        static_cast<char>(0xffu)
     };
     EXPECT_EQ(memcmp(sbuf.data(), packed, sizeof(packed)), 0);
 
@@ -959,28 +963,28 @@ TEST(MSGPACK_CHRONO, system_clock_64_max)
     msgpack::sbuffer sbuf;
     msgpack::pack(sbuf, val1);
     char packed_nano[] = {
-        static_cast<char>(0xd7),
+        static_cast<char>(0xd7u),
         static_cast<char>(-1),
-        static_cast<char>(0xee), // 999,999,999 << 2
+        static_cast<char>(0xeeu), // 999,999,999 << 2
         static_cast<char>(0x6b),
         static_cast<char>(0x27),
-        static_cast<char>(0xfc),
-        static_cast<char>(0xff), // 32 bit sec
-        static_cast<char>(0xff),
-        static_cast<char>(0xff),
-        static_cast<char>(0xff)
+        static_cast<char>(0xfcu),
+        static_cast<char>(0xffu), // 32 bit sec
+        static_cast<char>(0xffu),
+        static_cast<char>(0xffu),
+        static_cast<char>(0xffu)
     };
     char packed_micro[] = {
-        static_cast<char>(0xd7),
+        static_cast<char>(0xd7u),
         static_cast<char>(-1),
-        static_cast<char>(0xee), // 999,999,000 << 2
+        static_cast<char>(0xeeu), // 999,999,000 << 2
         static_cast<char>(0x6b),
         static_cast<char>(0x18),
         static_cast<char>(0x60),
-        static_cast<char>(0xff), // 32 bit sec
-        static_cast<char>(0xff),
-        static_cast<char>(0xff),
-        static_cast<char>(0xff)
+        static_cast<char>(0xffu), // 32 bit sec
+        static_cast<char>(0xffu),
+        static_cast<char>(0xffu),
+        static_cast<char>(0xffu)
     };
     if (std::chrono::system_clock::duration::period::ratio::den == 1000000000) {
         EXPECT_EQ(memcmp(sbuf.data(), packed_nano, sizeof(packed_nano)), 0);
@@ -1056,7 +1060,7 @@ TEST(MSGPACK_TIMESPEC, timespec_pack_convert_zero)
 
     msgpack::pack(ss, val1);
     std::string const& str = ss.str();
-    EXPECT_EQ(str.data()[0], static_cast<char>(0xd6));
+    EXPECT_EQ(str.data()[0], static_cast<char>(0xd6u));
 
     msgpack::object_handle oh;
     msgpack::unpack(oh, str.data(), str.size());
@@ -1082,7 +1086,7 @@ TEST(MSGPACK_TIMESPEC, timespec_pack_convert_32bit_sec)
 
     msgpack::pack(ss, val1);
     std::string const& str = ss.str();
-    EXPECT_EQ(str.data()[0], static_cast<char>(0xd6));
+    EXPECT_EQ(str.data()[0], static_cast<char>(0xd6u));
 
     msgpack::object_handle oh;
     msgpack::unpack(oh, str.data(), str.size());
@@ -1108,7 +1112,7 @@ TEST(MSGPACK_TIMESPEC, timespec_pack_convert_max_nano)
 
     msgpack::pack(ss, val1);
     std::string const& str = ss.str();
-    EXPECT_EQ(str.data()[0], static_cast<char>(0xd7));
+    EXPECT_EQ(str.data()[0], static_cast<char>(0xd7u));
     msgpack::object_handle oh;
     msgpack::unpack(oh, str.data(), str.size());
     timespec val2 = oh.get().as<timespec>();
@@ -1134,7 +1138,7 @@ TEST(MSGPACK_TIMESPEC, timespec_pack_convert_34bit_sec_max_nano)
 
     msgpack::pack(ss, val1);
     std::string const& str = ss.str();
-    EXPECT_EQ(str.data()[0], static_cast<char>(0xd7));
+    EXPECT_EQ(str.data()[0], static_cast<char>(0xd7u));
 
     msgpack::object_handle oh;
     msgpack::unpack(oh, str.data(), str.size());
@@ -1162,7 +1166,7 @@ TEST(MSGPACK_TIMESPEC, timespec_pack_convert_35bit_sec_max_nano)
 
     msgpack::pack(ss, val1);
     std::string const& str = ss.str();
-    EXPECT_EQ(str.data()[0], static_cast<char>(0xc7));
+    EXPECT_EQ(str.data()[0], static_cast<char>(0xc7u));
 
     msgpack::object_handle oh;
     msgpack::unpack(oh, str.data(), str.size());
@@ -1189,7 +1193,7 @@ TEST(MSGPACK_TIMESPEC, timespec_pack_convert_64bit_sec_max_nano)
 
     msgpack::pack(ss, val1);
     std::string const& str = ss.str();
-    EXPECT_EQ(str.data()[0], static_cast<char>(0xc7));
+    EXPECT_EQ(str.data()[0], static_cast<char>(0xc7u));
 
     msgpack::object_handle oh;
     msgpack::unpack(oh, str.data(), str.size());
diff --git a/test/msgpack_cpp17.cpp b/test/msgpack_cpp17.cpp
index 93234172..b0c29e5e 100644
--- a/test/msgpack_cpp17.cpp
+++ b/test/msgpack_cpp17.cpp
@@ -1,11 +1,15 @@
 #include <msgpack.hpp>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
diff --git a/test/msgpack_stream.cpp b/test/msgpack_stream.cpp
index 4369b50c..2c67196b 100644
--- a/test/msgpack_stream.cpp
+++ b/test/msgpack_stream.cpp
@@ -9,12 +9,16 @@
 #include <list>
 #include <limits>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
diff --git a/test/msgpack_tuple.cpp b/test/msgpack_tuple.cpp
index e7113648..ffb75d56 100644
--- a/test/msgpack_tuple.cpp
+++ b/test/msgpack_tuple.cpp
@@ -1,12 +1,15 @@
 #include <msgpack.hpp>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
-
+#endif //defined(__GNUC__)
 
 TEST(msgpack_tuple, member_get)
 {
diff --git a/test/msgpack_vref.cpp b/test/msgpack_vref.cpp
index 20fb0622..1bccf07b 100644
--- a/test/msgpack_vref.cpp
+++ b/test/msgpack_vref.cpp
@@ -9,12 +9,16 @@
 #include <list>
 #include <limits>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
diff --git a/test/msgpack_x3_parse.cpp b/test/msgpack_x3_parse.cpp
index 3dbd900e..7fe6748f 100644
--- a/test/msgpack_x3_parse.cpp
+++ b/test/msgpack_x3_parse.cpp
@@ -4,12 +4,16 @@
 #include <limits>
 #include <cmath>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 // To avoid link error
 TEST(MSGPACK_X3_PARSE, dummy)
diff --git a/test/object.cpp b/test/object.cpp
index 9095dab8..6cc68b4b 100644
--- a/test/object.cpp
+++ b/test/object.cpp
@@ -1,12 +1,15 @@
 #include <msgpack.hpp>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
-
+#endif //defined(__GNUC__)
 
 enum enum_test {
     elem
diff --git a/test/object_with_zone.cpp b/test/object_with_zone.cpp
index df71418f..7337811d 100644
--- a/test/object_with_zone.cpp
+++ b/test/object_with_zone.cpp
@@ -1,11 +1,15 @@
 #include <msgpack.hpp>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #include <cmath>
 
diff --git a/test/pack_unpack.cpp b/test/pack_unpack.cpp
index f29e2001..28dd27b4 100644
--- a/test/pack_unpack.cpp
+++ b/test/pack_unpack.cpp
@@ -1,11 +1,15 @@
 #include <msgpack.hpp>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #include <sstream>
 
@@ -524,7 +528,7 @@ TEST(unpack, int_off_larger_than_length)
 TEST(unpack, empty_array_fix)
 {
     std::string buf;
-    buf.push_back(static_cast<char>(0x90));
+    buf.push_back(static_cast<char>(0x90u));
     std::size_t off = 0;
 
     msgpack::object_handle oh = msgpack::unpack(buf.data(), buf.size(), off);
@@ -536,7 +540,7 @@ TEST(unpack, empty_array_fix)
 TEST(unpack, empty_array_16)
 {
     std::string buf;
-    buf.push_back(static_cast<char>(0xdc));
+    buf.push_back(static_cast<char>(0xdcu));
     buf.push_back(static_cast<char>(0x00));
     buf.push_back(static_cast<char>(0x00));
     std::size_t off = 0;
@@ -550,7 +554,7 @@ TEST(unpack, empty_array_16)
 TEST(unpack, empty_array_32)
 {
     std::string buf;
-    buf.push_back(static_cast<char>(0xdd));
+    buf.push_back(static_cast<char>(0xddu));
     buf.push_back(static_cast<char>(0x00));
     buf.push_back(static_cast<char>(0x00));
     buf.push_back(static_cast<char>(0x00));
@@ -566,7 +570,7 @@ TEST(unpack, empty_array_32)
 TEST(unpack, empty_map_fix)
 {
     std::string buf;
-    buf.push_back(static_cast<char>(0x80));
+    buf.push_back(static_cast<char>(0x80u));
     std::size_t off = 0;
 
     msgpack::object_handle oh = msgpack::unpack(buf.data(), buf.size(), off);
@@ -578,7 +582,7 @@ TEST(unpack, empty_map_fix)
 TEST(unpack, empty_map_16)
 {
     std::string buf;
-    buf.push_back(static_cast<char>(0xde));
+    buf.push_back(static_cast<char>(0xdeu));
     buf.push_back(static_cast<char>(0x00));
     buf.push_back(static_cast<char>(0x00));
     std::size_t off = 0;
@@ -592,7 +596,7 @@ TEST(unpack, empty_map_16)
 TEST(unpack, empty_map_32)
 {
     std::string buf;
-    buf.push_back(static_cast<char>(0xdf));
+    buf.push_back(static_cast<char>(0xdfu));
     buf.push_back(static_cast<char>(0x00));
     buf.push_back(static_cast<char>(0x00));
     buf.push_back(static_cast<char>(0x00));
diff --git a/test/pack_unpack_c.cpp b/test/pack_unpack_c.cpp
index 8c35f991..7a9b3b96 100644
--- a/test/pack_unpack_c.cpp
+++ b/test/pack_unpack_c.cpp
@@ -1,11 +1,15 @@
 #include <msgpack.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #include <stdio.h>
 
diff --git a/test/raw.cpp b/test/raw.cpp
index a3cfc313..0d7eafcc 100644
--- a/test/raw.cpp
+++ b/test/raw.cpp
@@ -3,12 +3,16 @@
 #include <string>
 #include <sstream>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
diff --git a/test/reference.cpp b/test/reference.cpp
index 77f67aa8..5ee127f4 100644
--- a/test/reference.cpp
+++ b/test/reference.cpp
@@ -1,11 +1,15 @@
 #include <msgpack.hpp>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 TEST(reference, unpack_int)
 {
diff --git a/test/reference_cpp11.cpp b/test/reference_cpp11.cpp
index 995065de..0faa2e21 100644
--- a/test/reference_cpp11.cpp
+++ b/test/reference_cpp11.cpp
@@ -1,11 +1,15 @@
 #include <msgpack.hpp>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #if !defined(MSGPACK_USE_CPP03)
 
diff --git a/test/reference_wrapper_cpp11.cpp b/test/reference_wrapper_cpp11.cpp
index b94ca88d..6507d827 100644
--- a/test/reference_wrapper_cpp11.cpp
+++ b/test/reference_wrapper_cpp11.cpp
@@ -1,12 +1,16 @@
 #include <msgpack.hpp>
 #include <sstream>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
diff --git a/test/shared_ptr_cpp11.cpp b/test/shared_ptr_cpp11.cpp
index 18f34574..91458f7e 100644
--- a/test/shared_ptr_cpp11.cpp
+++ b/test/shared_ptr_cpp11.cpp
@@ -2,12 +2,16 @@
 #include <sstream>
 #include <iterator>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
diff --git a/test/size_equal_only.cpp b/test/size_equal_only.cpp
index 0fe53ef9..0a8b2611 100644
--- a/test/size_equal_only.cpp
+++ b/test/size_equal_only.cpp
@@ -1,12 +1,16 @@
 #include <sstream>
 #include <msgpack.hpp>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 TEST(size_equal_only, array)
 {
diff --git a/test/streaming.cpp b/test/streaming.cpp
index def6a7e9..f625cc0a 100644
--- a/test/streaming.cpp
+++ b/test/streaming.cpp
@@ -1,11 +1,15 @@
 #include <msgpack.hpp>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #include <sstream>
 
diff --git a/test/streaming_c.cpp b/test/streaming_c.cpp
index f59f15c6..d75bfbe5 100644
--- a/test/streaming_c.cpp
+++ b/test/streaming_c.cpp
@@ -1,11 +1,15 @@
 #include <msgpack.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #include <stdio.h>
 
diff --git a/test/unique_ptr_cpp11.cpp b/test/unique_ptr_cpp11.cpp
index d28e94e2..483f4bb2 100644
--- a/test/unique_ptr_cpp11.cpp
+++ b/test/unique_ptr_cpp11.cpp
@@ -2,12 +2,16 @@
 #include <sstream>
 #include <iterator>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
diff --git a/test/user_class.cpp b/test/user_class.cpp
index 77b2c089..5c3185cf 100644
--- a/test/user_class.cpp
+++ b/test/user_class.cpp
@@ -2,12 +2,16 @@
 #include <string>
 #include <cmath>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
diff --git a/test/version.cpp b/test/version.cpp
index 78c3bfaa..d9d5cc5c 100644
--- a/test/version.cpp
+++ b/test/version.cpp
@@ -1,11 +1,15 @@
 #include <msgpack.hpp>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 TEST(version, print)
 {
diff --git a/test/visitor.cpp b/test/visitor.cpp
index c3faa69c..4e0a7cd8 100644
--- a/test/visitor.cpp
+++ b/test/visitor.cpp
@@ -1,11 +1,15 @@
 #include <msgpack.hpp>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 #include <sstream>
 
diff --git a/test/zone.cpp b/test/zone.cpp
index e0acb5fd..2a851107 100644
--- a/test/zone.cpp
+++ b/test/zone.cpp
@@ -1,11 +1,15 @@
 #include <msgpack.hpp>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wconversion"
+#endif //defined(__GNUC__)
 
 #include <gtest/gtest.h>
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic pop
+#endif //defined(__GNUC__)
 
 TEST(zone, allocate_align)
 {