diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 243d3b079..71e58732c 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -2,23 +2,50 @@ name: CI
 
 on:
   push:
-    branches: [ master, dev ]
+    branches: [ master, dev, windows_compatibility ]
   pull_request:
     branches: [ master ]
 
 jobs:
-  build:
+  build-msys2-clang:
+    runs-on: windows-latest
+    strategy:
+      matrix:
+        build_type: [Release, Debug]
+    defaults:
+      run:
+        shell: msys2 {0}
+    steps:
+      - uses: actions/checkout@v2
+
+      - uses: msys2/setup-msys2@v2
+        with:
+          msystem: CLANG64
+          update: true
+          install: git binutils mingw-w64-clang-x86_64-cmake mingw-w64-clang-x86_64-toolchain
+
+      - name: CMake
+        run: |
+          mkdir build && cd build
+          /clang64/bin/cmake .. -G "MinGW Makefiles" -DCMAKE_BUILD_TYPE=${{ matrix.build_type }}
+          /clang64/bin/cmake --build .
+      - name: Build testproject
+        run: |
+          cd resources/testproject
+          ../../build/c3c build
+
+  build-linux:
     runs-on: ubuntu-latest
     strategy:
       matrix:
         build_type: [Release, Debug]
-        
+
     steps:
       - uses: actions/checkout@v1
       - name: (Ubuntu) Download LLVM
         run: |
           sudo apt-get install zlib1g zlib1g-dev clang-11 libllvm11 llvm-11 llvm-11-dev llvm-11-runtime liblld-11-dev liblld-11
-          
+
       - name: CMake
         run: |
           mkdir build && cd build
diff --git a/CMakeLists.txt b/CMakeLists.txt
index b41798e96..efb134261 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -161,5 +161,12 @@ target_link_libraries(c3c_wrappers ${llvm_libs} ${lld_libs})
 #target_link_libraries(c3c m ${llvm_libs} c3c_wrappers lldCommon lldCore lldCOFF lldWASM lldMinGW lldELF lldDriver lldReaderWriter lldMachO lldYAML)
 target_link_libraries(c3c m ${llvm_libs} c3c_wrappers ${lld_libs})
 
+if (WIN32)
+    if (CMAKE_C_COMPILER_ID STREQUAL "Clang" OR CMAKE_C_COMPILE_ID STREQUAL "GNU")
+        target_link_options(c3c PRIVATE -pthread)
+        target_compile_definitions(c3c PRIVATE USE_PTHREAD=1)
+    endif()
+endif()
+
 install(TARGETS c3c DESTINATION bin)
 
diff --git a/src/utils/common.h b/src/utils/common.h
index 03d25ed65..3633ca3de 100644
--- a/src/utils/common.h
+++ b/src/utils/common.h
@@ -28,11 +28,13 @@
 #define PLATFORM_POSIX 1
 #endif
 
+#ifndef USE_PTHREAD
 #if PLATFORM_POSIX
 #define USE_PTHREAD 1
 #else
 #define USE_PTHREAD 0
 #endif
+#endif
 
 #define IS_GCC 0
 #define IS_CLANG 0