diff --git a/appveyor.yml b/appveyor.yml
index ed39010..2395a42 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -49,7 +49,7 @@ install:
       ) {
         cd C:\Tools\vcpkg
         git pull
-        cd %APPVEYOR_BUILD_FOLDER%
+        cd "$env:APPVEYOR_BUILD_FOLDER"
       }
 
 before_build: