diff --git a/.github/workflows/gha.yml b/.github/workflows/gha.yml
index 4abe45fe5..0f9de4418 100644
--- a/.github/workflows/gha.yml
+++ b/.github/workflows/gha.yml
@@ -21,6 +21,7 @@ jobs:
     - name: Checkout
       uses: actions/checkout@v3
     - name: Install Dependencies
+      run: |
         brew update
         brew install --force llvm
 
@@ -59,7 +60,7 @@ jobs:
 
         case ${{ matrix.pattern }} in
           0)
-            export MSGPACK_CXX_VERSION="MSGPACK_CXX11=OFF"
+            export MSGPACK_CXX_VERSION="MSGPACK_CXX11=ON"
             ;;
           1)
             export API_VERSION=1
@@ -136,7 +137,7 @@ jobs:
         case ${{ matrix.pattern }} in
           0)
             export CXX="clang++-10"
-            export MSGPACK_CXX_VERSION="MSGPACK_CXX11=OFF"
+            export MSGPACK_CXX_VERSION="MSGPACK_CXX11=ON"
             ;;
           1)
             export CXX="g++-10"
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8dc6d610a..a6dd2bcd1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,6 +1,12 @@
-CMAKE_MINIMUM_REQUIRED (VERSION 3.1 FATAL_ERROR)
-
-CMAKE_POLICY (SET CMP0054 NEW)
+if(${CMAKE_VERSION} VERSION_GREATER "3.4")
+    CMAKE_MINIMUM_REQUIRED (VERSION 3.5)
+else()
+    CMAKE_MINIMUM_REQUIRED (VERSION 2.8.12)
+    IF ((CMAKE_VERSION VERSION_GREATER 3.1) OR
+        (CMAKE_VERSION VERSION_EQUAL 3.1))
+        CMAKE_POLICY(SET CMP0054 NEW)
+    ENDIF ()
+endif()
 
 PROJECT (msgpack-cxx LANGUAGES CXX)
 
@@ -18,7 +24,7 @@ SET (VERSION ${VERSION_MAJOR}.${VERSION_MINOR}.${VERSION_REVISION})
 LIST (APPEND CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake/")
 SET (GNUCXX_STD_SUPPORT_VERSION "4.3")
 
-OPTION (MSGPACK_CXX11 "Using c++11 compiler" OFF)
+OPTION (MSGPACK_CXX11 "Using c++11 compiler" ON)
 OPTION (MSGPACK_CXX14 "Using c++14 compiler" OFF)
 OPTION (MSGPACK_CXX17 "Using c++17 compiler" OFF)
 OPTION (MSGPACK_CXX20 "Using c++20 compiler" OFF)
@@ -67,6 +73,10 @@ IF (MSGPACK_32BIT)
 ENDIF ()
 
 IF (MSGPACK_USE_BOOST)
+    IF ((CMAKE_VERSION VERSION_GREATER 3.30) OR
+        (CMAKE_VERSION VERSION_EQUAL 3.30))
+        CMAKE_POLICY(SET CMP0167 NEW)
+    ENDIF ()
     SET (Boost_USE_MULTITHREADED ON)
 
     IF (MSGPACK_USE_STATIC_BOOST)
@@ -143,6 +153,13 @@ IF (MSGPACK_GEN_COVERAGE)
 ENDIF ()
 
 IF (MSGPACK_BUILD_TESTS)
+    IF (${CMAKE_CXX_STANDARD} EQUAL 98)
+        MESSAGE (FATAL_ERROR "Tests requires C++11 or newer")
+    ENDIF ()
+    IF ((CMAKE_VERSION VERSION_GREATER 3.27) OR
+        (CMAKE_VERSION VERSION_EQUAL 3.27))
+        CMAKE_POLICY(SET CMP0145 OLD)
+    ENDIF ()
     IF (NOT MSGPACK_USE_BOOST)
         MESSAGE(FATAL_ERROR "Test requires -DMSGPACK_USE_BOOST=ON")
     ENDIF ()
diff --git a/appveyor.yml b/appveyor.yml
index bcd23d817..cf7e44693 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -6,16 +6,6 @@ branches:
 
 environment:
   matrix:
-    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2013
-      cpp11: -DMSGPACK_CXX11=OFF
-      msvc: '"Visual Studio 12 2013"'
-      boost_prefix: C:\Libraries\boost_1_58_0
-      boost_subdir: lib32-msvc-12.0
-    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
-      cpp11: -DMSGPACK_CXX11=OFF
-      msvc: '"Visual Studio 14 2015"'
-      boost_prefix: C:\Libraries\boost_1_69_0
-      boost_subdir: lib32-msvc-14.0
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
       cpp11: -DMSGPACK_CXX11=ON
       msvc: '"Visual Studio 14 2015"'
diff --git a/include/msgpack/type.hpp b/include/msgpack/type.hpp
index 1ab49745f..9ef3e86d3 100644
--- a/include/msgpack/type.hpp
+++ b/include/msgpack/type.hpp
@@ -73,7 +73,11 @@
 
 #if !defined(MSGPACK_NO_BOOST)
 #include "adaptor/boost/fusion.hpp"
+
+#if !defined(MSGPACK_USE_CPP03)
 #include "adaptor/boost/msgpack_variant.hpp"
+#endif // !defined(MSGPACK_USE_CPP03)
+
 #include "adaptor/boost/optional.hpp"
 #include "adaptor/boost/string_ref.hpp"
 #include "adaptor/boost/string_view.hpp"
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index a0233dd35..b29c07a2c 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -8,7 +8,6 @@ LIST (APPEND check_PROGRAMS
     boost_optional.cpp
     boost_string_ref.cpp
     boost_string_view.cpp
-    boost_variant.cpp
     buffer.cpp
     carray.cpp
     cases.cpp
@@ -43,6 +42,7 @@ ENDIF ()
 
 IF (MSGPACK_CXX11 OR MSGPACK_CXX14 OR MSGPACK_CXX17 OR MSGPACK_CXX20)
     LIST (APPEND check_PROGRAMS
+        boost_variant.cpp
         iterator_cpp11.cpp
         msgpack_cpp11.cpp
         reference_cpp11.cpp