diff --git a/classes/Cart.php b/classes/Cart.php
index 1dda83cb7..c84060653 100644
--- a/classes/Cart.php
+++ b/classes/Cart.php
@@ -2965,7 +2965,7 @@ class CartCore extends ObjectModel
 	{
 		$sql = 'SELECT c.`id_cart`
 				FROM '._DB_PREFIX_.'cart c
-				WHERE c.`id_cart` NOT IN (SELECT o.`id_cart` FROM '._DB_PREFIX_.'orders o)
+				WHERE c.`id_cart` NOT IN (SELECT o.`id_cart` FROM '._DB_PREFIX_.'orders o WHERE o.`id_customer` = '.(int)$id_customer.')
 				AND c.`id_customer` = '.(int)$id_customer.'
 					'.Shop::addSqlRestriction(Shop::SHARE_ORDER, 'c').'
 				ORDER BY c.`date_upd` DESC';
@@ -2973,7 +2973,7 @@ class CartCore extends ObjectModel
 		if (!$id_cart = Db::getInstance()->getValue($sql))
 			return false;
 
-		return $id_cart;
+		return (int)$id_cart;
 	}
 
 	/**