diff --git a/appveyor.yml b/appveyor.yml
index 258b330..1c7c3ba 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -48,7 +48,8 @@ before_build:
   - mkdir %BUILD_HOME%
   - cd %BUILD_HOME%
   - cmake -G "%GENERATOR%" 
-    -DBUILD_TESTS=1
+    -DBUILD_TESTS=1 
+    -DGEN_X=1
     -DBOOST_ROOT="%BOOST_ROOT%"
     -DBoost_USE_STATIC_LIBS="ON" ..