diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
index 019d1e66e..116617c27 100644
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -19,5 +19,5 @@ jobs:
         uses: GoogleCloudPlatform/php-tools/.github/workflows/doctum.yml@main
         with:
           title: "Google API Core (GAX) Reference Documentation"
-          default_version: ${{ inputs.tag || github.event.pull_request.head.repo.full_name || github.head_ref }}
+          default_version: ${{ inputs.tag || github.head_ref || 'main' }}
           dry_run: ${{ github.event_name == 'pull_request' }}