diff --git a/.github/workflows/rename-module.yml b/.github/workflows/rename-module.yml
index 54d9f9a6ad46..379f7fceba80 100644
--- a/.github/workflows/rename-module.yml
+++ b/.github/workflows/rename-module.yml
@@ -9,21 +9,22 @@ on:
         description: 'Upstream commit on which to base module renaming'
         required: true
         type: string
-        default: '2bd6bd01d2e8561dd7fc21b631f4a34ac16627a1'
+        default: ''
 
 jobs:
   rename-module:
     runs-on: ubuntu-latest
     env:
-      output_branch: "${{ github.ref_name }}_auto-rename-module-${{ inputs.source_commit }}"
+      source_commit: ${{ inputs.source_commit || '2bd6bd01d2e8561dd7fc21b631f4a34ac16627a1' }}
+      output_branch: "${{ github.ref_name }}_auto-rename-module-${{ env.source_commit }}"
     steps:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0 # everything
           fetch-tags: true
 
-      - name: Check out source commit
-        run: git checkout ${{ inputs.source_commit }}
+      - name: Check out source commit `{{ $env.source_commit }}`
+        run: git checkout ${{ env.source_commit }}
 
       - name: Globally update module name
         run: |
@@ -62,11 +63,11 @@ jobs:
           commit_prefix: "[AUTO] rename Go module + update internal import paths"
 
       - name: Open PR to "renamed-go-module" iff workflow dispatched on "main"
-        # if: github.event_name == 'workflow_dispatch' && github.ref != 'refs/heads/main'
+        if: github.event_name == 'workflow_dispatch' && github.ref != 'refs/heads/main'
         uses: devops-infra/action-pull-request@v0.5.5
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           source_branch: ${{ env.output_branch }}
           target_branch: renamed-go-module
-          title: "[AUTO] Rename upstream Go module at `${{ inputs.source_commit }}`"
+          title: "[AUTO] Rename upstream Go module at `${{ env.source_commit }}`"
           body: "_PR generated by GitHub Action_"