diff --git a/.github/workflows/update-pr-metadata.yml b/.github/workflows/update-pr-metadata.yml
index 23be5b39d..081f9fe0e 100644
--- a/.github/workflows/update-pr-metadata.yml
+++ b/.github/workflows/update-pr-metadata.yml
@@ -24,11 +24,14 @@ jobs:
           github-token: ${{ github.token }}
 
       - name: Add assignees
-        if: github.event_name == 'pull_request'
+        if: |
+          github.event_name == 'pull_request' &&
+          contains(fromJson('["opened", "reopened"]'), github.event.action) &&
+          !endsWith(github.event.pull_request.user.login, '[bot]')
         uses: actions-ecosystem/action-add-assignees@v1
         with:
           github_token: ${{ github.token }}
-          assignees: ${{ github.actor }}
+          assignees: ${{ github.event.pull_request.user.login }}
 
   pr-size-diff:
     runs-on: ubuntu-latest