diff --git a/install-dev/upgrade/php/add_order_reference_in_order_payment.php b/install-dev/upgrade/php/add_order_reference_in_order_payment.php
index 2d082924d..982fa5bd3 100644
--- a/install-dev/upgrade/php/add_order_reference_in_order_payment.php
+++ b/install-dev/upgrade/php/add_order_reference_in_order_payment.php
@@ -27,6 +27,7 @@
 
 function add_order_reference_in_order_payment()
 {
+	$res = true;
 	$payments = Db::getInstance()->executeS('
 	SELECT op.id_order_payment, o.reference
 	FROM `'._DB_PREFIX_.'order_payment` op
@@ -86,4 +87,4 @@ function add_order_reference_in_order_payment()
 		return array('errors' => true, 'msg' =>  Db::getInstance()->getMsgError());
 	
 	return true;
-}
\ No newline at end of file
+}