diff --git a/Entities/Approval.php b/Entities/Approval.php
index eeedd02..7366e02 100644
--- a/Entities/Approval.php
+++ b/Entities/Approval.php
@@ -16,5 +16,6 @@
             'updated_by',
             'deleted_by',
             'approved_by',
+            'ref'
         ];
     }