diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 71e58732c..13489b138 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -2,11 +2,44 @@ name: CI
 
 on:
   push:
-    branches: [ master, dev, windows_compatibility ]
+    branches: [ master, dev, ci_testing ]
   pull_request:
     branches: [ master ]
 
 jobs:
+  build-msys2-mingw:
+    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: MINGW64
+          update: true
+          install: git binutils mingw-w64-x86_64-cmake mingw-w64-x86_64-toolchain mingw-w64-x86_64-llvm mingw-w64-x86_64-polly mingw-w64-x86_64-python mingw-w64-x86_64-lld
+
+      - name: CMake
+        run: |
+          mkdir build && cd build
+          cmake .. -G "MinGW Makefiles" -DCMAKE_BUILD_TYPE=${{ matrix.build_type }}
+          cmake --build .
+
+      - name: Build testproject
+        run: |
+          cd resources/testproject
+          ../../build/c3c build
+
+      - name: run compiler tests
+        run: |
+          cd test
+          python3 src/tester.py ../build/c3c.exe test_suite/
+
   build-msys2-clang:
     runs-on: windows-latest
     strategy:
@@ -22,18 +55,23 @@ jobs:
         with:
           msystem: CLANG64
           update: true
-          install: git binutils mingw-w64-clang-x86_64-cmake mingw-w64-clang-x86_64-toolchain
+          install: git binutils mingw-w64-clang-x86_64-cmake mingw-w64-clang-x86_64-toolchain mingw-w64-clang-x86_64-python
 
       - name: CMake
         run: |
           mkdir build && cd build
-          /clang64/bin/cmake .. -G "MinGW Makefiles" -DCMAKE_BUILD_TYPE=${{ matrix.build_type }}
-          /clang64/bin/cmake --build .
+          cmake .. -G "MinGW Makefiles" -DCMAKE_BUILD_TYPE=${{ matrix.build_type }}
+          cmake --build .
       - name: Build testproject
         run: |
           cd resources/testproject
           ../../build/c3c build
 
+      - name: run compiler tests
+        run: |
+          cd test
+          python3 src/tester.py ../build/c3c.exe test_suite/
+
   build-linux:
     runs-on: ubuntu-latest
     strategy:
@@ -44,7 +82,7 @@ jobs:
       - 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
+          sudo apt-get install zlib1g zlib1g-dev clang-11 libllvm11 llvm-11 llvm-11-dev llvm-11-runtime liblld-11-dev liblld-11 python3
 
       - name: CMake
         run: |
@@ -56,3 +94,8 @@ jobs:
         run: |
           cd resources/testproject
           ../../build/c3c build
+
+      - name: run compiler tests
+        run: |
+          cd test
+          python3 src/tester.py ../build/c3c test_suite/
diff --git a/CMakeLists.txt b/CMakeLists.txt
index efb134261..426d6dde5 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -165,6 +165,7 @@ 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)
+        target_compile_options(c3c PRIVATE -mlong-double-64)
     endif()
 endif()
 
diff --git a/src/utils/file_utils.c b/src/utils/file_utils.c
index 45bd19bc7..1c098b7b2 100644
--- a/src/utils/file_utils.c
+++ b/src/utils/file_utils.c
@@ -104,7 +104,7 @@ const char* find_lib_dir(void)
 	struct stat info;
 	char *lib_path = NULL;
 
-	asprintf(&lib_path, "%s../lib/std/", path);
+	asprintf(&lib_path, "%s../lib/std", path);
 	DEBUG_LOG("Checking %s", lib_path);
 	int err = stat(lib_path, &info);
 
@@ -115,7 +115,7 @@ const char* find_lib_dir(void)
 		return lib_path;
 	}
 
-	asprintf(&lib_path, "%slib/std/", path);
+	asprintf(&lib_path, "%slib/std", path);
 	err = stat(lib_path, &info);
 
 	// Found it at ./lib/std
@@ -225,6 +225,10 @@ char *realpath(const char *path, char *const resolved_path)
 		if (NULL == resolved_path) free(result);
 		return NULL;
 	}
+	for (char *c = result; *c != '\0'; ++c)
+	{
+		if ('\\' == *c) *c = '/';
+	}
 	return result;
 }
 
diff --git a/src/utils/whereami.c b/src/utils/whereami.c
index af007a312..104bbae77 100644
--- a/src/utils/whereami.c
+++ b/src/utils/whereami.c
@@ -416,6 +416,10 @@ const char *find_executable_path(void)
 	char *path = malloc(len + 1);
 	get_executable_path_raw(path, len, NULL);
 	path[len] = '\0';
+	for (int i = 0; i < len; ++i)
+	{
+		if ('\\' == path[i]) path[i] = '/';
+	}
 	for (int i = len - 1; i >= 0; i--)
 	{
 		switch (path[i])
diff --git a/test/src/tester.py b/test/src/tester.py
index 2307463a5..fab011acb 100644
--- a/test/src/tester.py
+++ b/test/src/tester.py
@@ -1,7 +1,7 @@
 #!/usr/bin/python
-import os, sys, shutil, subprocess
+import os, sys, shutil, subprocess, tempfile
 
-TEST_DIR = '/tmp/c3test/'
+TEST_DIR = tempfile.mkdtemp().replace('\\', '/') + '/c3test/'
 
 class Config:
     run_skipped = False