diff --git a/.github/workflows/update-downstream.yml b/.github/workflows/update-downstream.yml
index 7e6e477..fd935d2 100644
--- a/.github/workflows/update-downstream.yml
+++ b/.github/workflows/update-downstream.yml
@@ -7,7 +7,7 @@ on:
 
 jobs:
   update-downstream-repos:
-    if: ${{ github.event.pull_request.merged }}
+    if: ${{ github.event.pull_request.merged == true && github.event.pull_request.base.ref == 'main' }}
     environment: detsys-pr-bot
     name: Pull request detsys-ts update to ${{ github.repository_owner }}/${{ matrix.repo }}
     runs-on: ubuntu-22.04
@@ -25,10 +25,10 @@ jobs:
       REF_URL: https://github.com/${{ github.repository }}/tree/${{ github.sha }}
       SOURCE_REPO: ${{ github.repository }}
       SOURCE_PR_NUMBER: ${{ github.event.pull_request.number }}
-      SOURCE_PR_URL: https://github.com/${{ github.repository }}/pull/${{ github.event.pull_request.number }}
-      HEAD_REF: ${{ github.head_ref }}
-      HEAD_COMMIT_MSG: ${{ github.event.head_commit.message }}
-      DIFF_URL: https://github.com/${{ github.repository }}/compare/${{ github.head_ref }}..${{ github.sha }}
+      SOURCE_PR_URL: ${{ github.event.pull_request.html_url }}
+      BASE_REF: ${{ github.event.pull_request.base.sha }}
+      DIFF_URL: https://github.com/${{ github.repository }}/compare/${{ github.event.pull_request.base.sha }}..${{ github.sha }}
+      DIFF_FILE_URL: ${{ github.event.pull_request.diff_url }}
       GIT_USER: ${{ github.actor }}
       GIT_EMAIL: ${{ github.actor }}@users.noreply.github.com
       GIT_BRANCH: detsys-ts-update-${{ github.sha }}
@@ -63,18 +63,27 @@ jobs:
           nix develop --command pnpm update detsys-ts
           nix develop --command pnpm all
 
+      - name: Get last commit message
+        id: commit-msg
+        run: |
+          MSG=$(git show -s --format=%s)
+          echo "msg=${MSG}" >> $GITHUB_OUTPUT
+
       - name: Create Pull Request
         uses: peter-evans/create-pull-request@v3
+        env:
+          COMMIT_MSG: ${{ steps.commit-msg.outputs.msg }}
         with:
           token: ${{ secrets.detsys_pr_bot_token }}
-          title: "Update `detsys-ts`: ${{ env.HEAD_COMMIT_MSG }}"
-          commit-message: "Update `detsys-ts` for: `${{ env.HEAD_COMMIT_MSG }}` (`${{ env.REF }}`)"
+          title: "Update `detsys-ts`: ${{ env.COMMIT_MSG }}"
+          commit-message: "Update `detsys-ts` for: `${{ env.COMMIT_MSG }}` (`${{ env.REF }}`)"
           body: |
             Bump [`detsys-ts`](${{ env.SOURCE_REPO }}) to the latest `HEAD` and regenerate application bundle.
 
             * Source ref: [`${{ env.REF }}`](${{ env.REF_URL }})
             * Source pull request: [`${{ env.SOURCE_REPO }}#${{ env.SOURCE_PR_NUMBER }}`](${{ env.SOURCE_PR_URL }})
-            * Source diff: [`${{ env.HEAD_REF }}..${{ env.REF }}`](${{ env.DIFF_URL }})
+            * Source diff: [`${{ env.BASE_REF }}..${{ env.REF }}`](${{ env.DIFF_URL }})
+            * Diff file: [`${{ env.SOURCE_PR_NUMBER }}.diff`](${{ env.DIFF_FILE_URL }})
           push-to-fork: detsys-pr-bot/${{ matrix.repo }}
           branch: "${{ env.GIT_BRANCH }}"
           base: ${{ env.GIT_BASE }}