diff --git a/.github/actions/argus-builder/manifest-update/action.yml b/.github/actions/argus-builder/manifest-update/action.yml
index 75584add..ee346864 100644
--- a/.github/actions/argus-builder/manifest-update/action.yml
+++ b/.github/actions/argus-builder/manifest-update/action.yml
@@ -37,6 +37,7 @@ runs:
       with:
         result-encoding: string
         script: |
+          const eventName = context.eventName;
           if (eventName === "pull_request") {
             // use PR head branch name if triggered by PR
             return context.payload.pull_request.head.ref;