diff --git a/htdocs/core/db/DoliDB.class.php b/htdocs/core/db/DoliDB.class.php
index 63dfa5a51f813..985dd15d5d816 100644
--- a/htdocs/core/db/DoliDB.class.php
+++ b/htdocs/core/db/DoliDB.class.php
@@ -247,7 +247,12 @@ public function order($sortfield = null, $sortorder = null)
 				if (!$return) $return .= ' ORDER BY ';
 				else $return .= ', ';
 
-				$return .= preg_replace('/[^0-9a-z_\.]/i', '', $val); // Add field
+				if (strpos($val, 'ref') !== false ){
+					$return  .= "lpad(".preg_replace('/[^0-9a-z_\.]/i', '', $val).", 30, '0')";
+					$val='';
+				} else {
+					$return .= preg_replace('/[^0-9a-z_\.]/i', '', $val); // Add field
+				}
 
 				$tmpsortorder = (empty($orders[$i]) ? '' : trim($orders[$i]));