diff --git a/action.yml b/action.yml
index 37fc25b..2ee6f78 100644
--- a/action.yml
+++ b/action.yml
@@ -91,7 +91,7 @@ runs:
         fi
 
         if [ -n "${{ inputs.extra }}" ]; then
-          extraopt="EXTRA=${{ inputs.extra }}"
+          extraopt="EXTRA='${{ inputs.extra }}'"
         fi
 
         ./run_test.sh RUNNER=${{inputs.runner}} --badgedir=$basedir/badges --junit-xml=$basedir/junit.xml --timeout=${{inputs.timeout}} $tagopt $nopt $extraopt || true