diff --git a/CI/MacOS/mac-build.yml b/CI/MacOS/mac-build.yml
index 8b5315681..d174358e9 100644
--- a/CI/MacOS/mac-build.yml
+++ b/CI/MacOS/mac-build.yml
@@ -10,7 +10,7 @@ steps:
     inputs:
       script: 'brew install qt'
       env:
-        HOMEBREW_NO_INSTALL_CLEANUP: 1
+        HOMEBREW_NO_INSTALL_CLEANUP: "1"
     displayName: 'Installing QT'
 
   - task: CmdLine@2