diff --git a/.github/workflows/cloudberry-backup-ci.yml b/.github/workflows/cloudberry-backup-ci.yml
index a3216337..5fe3f75e 100644
--- a/.github/workflows/cloudberry-backup-ci.yml
+++ b/.github/workflows/cloudberry-backup-ci.yml
@@ -53,7 +53,9 @@ permissions:
 
 env:
   CLOUDBERRY_REPO: apache/cloudberry
-  CLOUDBERRY_REF: main
+  # Currently targeting REL_2_STABLE (2.x) branch only.
+  # TODO: Switch back to "main" once Cloudberry 3.x / main branch stabilizes with PG16 support.
+  CLOUDBERRY_REF: REL_2_STABLE
   CLOUDBERRY_DIR: cloudberry
   CLOUDBERRY_BACKUP_DIR: cloudberry-backup