diff --git a/htdocs/comm/propal/class/propal.class.php b/htdocs/comm/propal/class/propal.class.php
index 68966bae711..f272120477f 100644
--- a/htdocs/comm/propal/class/propal.class.php
+++ b/htdocs/comm/propal/class/propal.class.php
@@ -1136,6 +1136,7 @@ class Propal extends CommonObject
         }
 
         $clonedObj->id=0;
+        $clonedObj->ref='';
         $clonedObj->statut=self::STATUS_DRAFT;
 
         // Clear fields