diff --git a/.github/workflows/comment-pr.yaml b/.github/workflows/comment-pr.yaml
index 92eafc51..4e16dab3 100644
--- a/.github/workflows/comment-pr.yaml
+++ b/.github/workflows/comment-pr.yaml
@@ -21,6 +21,7 @@ jobs:
             json_diff_file_output: diff.json
             raw_diff_file_output: diff.txt
             file_output_only: "true"
+            base_branch: ${{ github.event.pull_request.base.sha }}
     - name: Summarize
       env:
         DIFF: ${{ steps.git-diff-action.outputs.raw-diff-path }}