diff --git a/.github/workflows/trigger-merge-checks.yml b/.github/workflows/trigger-merge-checks.yml
index 905e264993..7dced04f2b 100644
--- a/.github/workflows/trigger-merge-checks.yml
+++ b/.github/workflows/trigger-merge-checks.yml
@@ -23,7 +23,7 @@ jobs:
             -H "Authorization: Bearer ${{ secrets.GITHUB_TOKEN }}" \
             -H "X-GitHub-Api-Version: 2022-11-28" \
             "https://api.github.com/repos/$GITHUB_REPOSITORY/actions/workflows/merge-checks.yml/dispatches" \
-            -d '{"ref":"${{ github.event.pull_request.head.sha }}"}'
+            -d '{"ref":"${{ github.head_ref }}"}'
       - name: Update merge-checks workflow run
         if: ${{ !contains(github.event.*.labels.*.name, 'design-approved') }}
         run: |
@@ -42,5 +42,5 @@ jobs:
               -H "Authorization: Bearer ${{ secrets.GITHUB_TOKEN }}" \
               -H "X-GitHub-Api-Version: 2022-11-28" \
               "https://api.github.com/repos/$GITHUB_REPOSITORY/actions/workflows/merge-checks.yml/dispatches" \
-              -d '{"ref":"${{ github.event.pull_request.head.sha }}"}'
+              -d '{"ref":"${{ github.head_ref }}"}'
           fi