diff --git a/.github/workflows/scorecard-scanner.yaml b/.github/workflows/scorecard-scanner.yaml
index 9585d116..e3424fe6 100644
--- a/.github/workflows/scorecard-scanner.yaml
+++ b/.github/workflows/scorecard-scanner.yaml
@@ -34,6 +34,8 @@ on:
   merge_group:
     types:
       - checks_requested
+    branches:
+      - main
 
   # Allow manual invocation.
   workflow_dispatch: