diff --git a/.github/workflows/label-merge-conflicts.yml b/.github/workflows/label-merge-conflicts.yml
index 2a435b736d..6eac6fc86b 100644
--- a/.github/workflows/label-merge-conflicts.yml
+++ b/.github/workflows/label-merge-conflicts.yml
@@ -5,6 +5,7 @@ on:
   push:
     branches:
       - master
+      - 4.0
   # Check conflicts in new PRs and for resolved conflicts due to an open PR being updated.
   pull_request_target:
     types: