diff --git a/src/Payment/API.php b/src/Payment/API.php
index 92a768547..3093e1185 100644
--- a/src/Payment/API.php
+++ b/src/Payment/API.php
@@ -81,6 +81,8 @@ public function __construct(Merchant $merchant)
      */
     public function pay(Order $order)
     {
+        $order['notify_url'] = $order['notify_url']? : $this->merchant->notify_url;
+        
         return $this->request(self::API_PAY_ORDER, $order->all());
     }
 
@@ -93,6 +95,8 @@ public function pay(Order $order)
      */
     public function prepare(Order $order)
     {
+        $order['notify_url'] = $order['notify_url']? : $this->merchant->notify_url;
+        
         return $this->request(self::API_PREPARE_ORDER, $order->all());
     }