diff --git a/.github/workflows/automate_merge_message.yml b/.github/workflows/automate_merge_message.yml
index aaeb0533a1..7ad4aa8fdd 100644
--- a/.github/workflows/automate_merge_message.yml
+++ b/.github/workflows/automate_merge_message.yml
@@ -25,7 +25,7 @@ jobs:
     steps:
       - uses: actions/checkout@v3
         with:
-          ref: '${{ github.event.pull_request.merge_commit_sha }}'
+          ref: '${{ github.event.pull_request.head.sha }}'
 
       - name: fetch base
         run: git fetch --depth 1 origin ${{ github.event.pull_request.base.sha }}