diff --git a/appveyor.yml b/appveyor.yml
index d8c9d4f5..aae7b16d 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -36,7 +36,7 @@ test_script:
   - if "%PLATFORM%" == "x64"
     call "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat" x86_amd64
   - set PATH=%PATH%;%QTDIR%\bin
-  - qmake DEFINES+=BOOST_INCLUDEDIR=C:\Libraries\boost_1_66_0 DEFINES+=CGAL_DIR=%APPVEYOR_BUILD_FOLDER%\CGAL-4.11.1
+  - qmake "DEFINES+=BOOST_INCLUDEDIR=C:\Libraries\boost_1_66_0" "DEFINES+=CGAL_DIR=%APPVEYOR_BUILD_FOLDER%\CGAL-4.11.1"
   - nmake -f Makefile.Release
     
 after_test: