diff --git a/.appveyor.yml b/.appveyor.yml
index 88583242..6ae27132 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -21,7 +21,7 @@ before_build:
   - mkdir build
   - cd build
   - cmake .. -G "Visual Studio 15 2017" 
-  - cmake --build . --target ALL_BUILD --config Debug
+  - cmake --build . --target ALL_BUILD --config Debug -DCMAKE_GENERATOR_PLATFORM=x64
 
 build_script:
   - cd ..