diff --git a/.appveyor.yml b/.appveyor.yml
index e7b47b00..d4e80d7b 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -43,9 +43,9 @@ before_build:
 
 build_script:
   - md build && cd build
-  - if %compiler%<>mingw ( set "CFLAGS=/MP%simultaneous% %CFLAGS%" )
-  - if %compiler%<>mingw ( set "CPPFLAGS=/MP%simultaneous% %CPPFLAGS%" )
-  - if %compiler%<>mingw ( set "CXXFLAGS=/MP%simultaneous% %CXXFLAGS%" )
+  - if not %compiler%==mingw ( set "CFLAGS=/MP%simultaneous% %CFLAGS%" )
+  - if not %compiler%==mingw ( set "CPPFLAGS=/MP%simultaneous% %CPPFLAGS%" )
+  - if not %compiler%==mingw ( set "CXXFLAGS=/MP%simultaneous% %CXXFLAGS%" )
   - cmake -G "%CMAKE_GENERATOR%" %CMAKE_FLAGS% ..
   - if %compiler%==mingw ( mingw32-make -j%simultaneous% tester examples )
     else ( msbuild /verbosity:diagnostic libui.sln /t:Build /p:Configuration=Release /p:Platform=%platform% )