diff --git a/appveyor.yml b/appveyor.yml
index 540ea9236..19187929f 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -11,7 +11,7 @@ build_script:
 
     cd build
 
-    cmake c:\Projects\chaiscript -G "%VS_VERSION%" -D BUILD_TESTING:BOOL=ON -D BUILD_MODULES:BOOL=ON
+    cmake c:\Projects\chaiscript -G "%VS_VERSION%" -DBUILD_TESTING:BOOL=ON -DBUILD_MODULES:BOOL=ON
 
     cmake --build . --config Debug
 test_script: