diff --git a/src/app/code/Komoju/Payments/Model/WebhookEvent.php b/src/app/code/Komoju/Payments/Model/WebhookEvent.php
index c18d28bf0..a99a955c8 100644
--- a/src/app/code/Komoju/Payments/Model/WebhookEvent.php
+++ b/src/app/code/Komoju/Payments/Model/WebhookEvent.php
@@ -28,7 +28,6 @@ public function __construct($requestBody)
 
         if (! empty(json_last_error())) {
             $errorMsg = (__("KOMOJU Payments JSON Decoding Failure. Error: %1", json_last_error_msg()));
-            
             throw new Komoju\Payments\Exception\InvalidJsonException($errorMsg);
         }
     }
@@ -62,7 +61,8 @@ public function status()
      */
     public function externalOrderNum()
     {
-        return $this->data()['external_order_num'];
+        $data = $this->data();
+        return isset($data['external_order_num']) ? $data['external_order_num'] : null;
     }
 
     /**