diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 3bf2ecfb..b78fd510 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -316,8 +316,9 @@ jobs:
           set s=%H%\src
           cat .GITREV.txt
           set /p GITREV=<.GITREV.txt
+          set UPX_DEFS=-DUPX_CONFIG_DISABLE_WSTRICT=0 -DUPX_CONFIG_DISABLE_WERROR=0 -DWITH_ZSTD=0
           set sources=%s%\*.cpp %s%\check\*.cpp %s%\compress\*.cpp %s%\console\*.cpp %s%\filter\*.cpp %s%\util\*.cpp
-          %RUN_CL% -std:c++17 -Zc:__cplusplus -EHsc -J -O2 -W4 -WX -DUPX_VERSION_GITREV="""%GITREV%""" -DWITH_ZSTD=0 %DEFS% -I%H%\vendor -Feupx.exe %sources% %BDIR%\ucl\ucl.lib %BDIR%\zlib\zlib.lib /link ${{ matrix.link_machine_flags }} setargv.obj
+          %RUN_CL% -std:c++17 -Zc:__cplusplus -EHsc -J -O2 -W4 -WX -DUPX_VERSION_GITREV="""%GITREV%""" %UPX_DEFS% %DEFS% -I%H%\vendor -Feupx.exe %sources% %BDIR%\ucl\ucl.lib %BDIR%\zlib\zlib.lib /link ${{ matrix.link_machine_flags }} setargv.obj
       - name: 'Make artifact'
         shell: bash
         run: |
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8a6f7572..a9f9bc27 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -256,11 +256,11 @@ endif()
 if(Threads_FOUND)
     target_compile_definitions(${t} PRIVATE WITH_THREADS=1)
 endif()
-if(UPX_CONFIG_DISABLE_WSTRICT)
-    target_compile_definitions(${t} PRIVATE UPX_CONFIG_DISABLE_WSTRICT=1)
+if(NOT UPX_CONFIG_DISABLE_WSTRICT)
+    target_compile_definitions(${t} PRIVATE UPX_CONFIG_DISABLE_WSTRICT=0)
 endif()
-if(UPX_CONFIG_DISABLE_WERROR)
-    target_compile_definitions(${t} PRIVATE UPX_CONFIG_DISABLE_WERROR=1)
+if(NOT UPX_CONFIG_DISABLE_WERROR)
+    target_compile_definitions(${t} PRIVATE UPX_CONFIG_DISABLE_WERROR=0)
 endif()
 if(NOT UPX_CONFIG_DISABLE_ZSTD)
     target_compile_definitions(${t} PRIVATE WITH_ZSTD=1)
diff --git a/src/conf.h b/src/conf.h
index b6457e4a..b4360508 100644
--- a/src/conf.h
+++ b/src/conf.h
@@ -48,7 +48,8 @@ ACC_COMPILE_TIME_ASSERT_HEADER(CHAR_MAX == 255) // -funsigned-char
 ACC_COMPILE_TIME_ASSERT_HEADER((char)(-1) == 255) // -funsigned-char
 
 // enable some more strict warnings for Git developer builds
-#if !UPX_CONFIG_DISABLE_WSTRICT && !UPX_CONFIG_DISABLE_WERROR
+#if defined(UPX_CONFIG_DISABLE_WSTRICT) && (UPX_CONFIG_DISABLE_WSTRICT + 0 == 0)
+#if defined(UPX_CONFIG_DISABLE_WERROR) && (UPX_CONFIG_DISABLE_WERROR + 0 == 0)
 #if (ACC_CC_CLANG >= 0x0b0000)
 #  pragma clang diagnostic error "-Wsuggest-override"
 #elif (ACC_CC_GNUC >= 0x0a0000)
@@ -70,7 +71,8 @@ ACC_COMPILE_TIME_ASSERT_HEADER((char)(-1) == 255) // -funsigned-char
 #  pragma warning(error: 4319)
 #  pragma warning(error: 4805)
 #endif
-#endif // !UPX_CONFIG_DISABLE_WSTRICT && !UPX_CONFIG_DISABLE_WERROR
+#endif // UPX_CONFIG_DISABLE_WSTRICT
+#endif // UPX_CONFIG_DISABLE_WERROR
 
 // multithreading (UPX currently does not use multithreading)
 #if (WITH_THREADS)