diff --git a/.github/workflows/sync_class_ref.yml b/.github/workflows/sync_class_ref.yml
index cae09d299..249fdaf1a 100644
--- a/.github/workflows/sync_class_ref.yml
+++ b/.github/workflows/sync_class_ref.yml
@@ -5,7 +5,7 @@ on:
 
 # Make sure jobs cannot overlap.
 concurrency:
-  group: classref-sync-ci
+  group: classref-sync-ci-3.5
   cancel-in-progress: true
 
 jobs: