diff --git a/action.yml b/action.yml
index f777d49..460a05b 100644
--- a/action.yml
+++ b/action.yml
@@ -18,7 +18,7 @@ inputs:
       When 'true', existing entries will be read from the cache but no entries will be written.
       By default this value is 'false' for workflows on the GitHub default branch and 'true' for workflows on other branches.
     required: false
-    default: ${{ github.event.repository && github.ref_name != github.event.repository.default_branch }}
+    default: ${{ github.event.repository != null && github.ref_name != github.event.repository.default_branch }}
 
   cache-write-only:
     description: |