diff --git a/app/code/Magento/SalesInventory/Test/Unit/Observer/RefundOrderInventoryObserverTest.php b/app/code/Magento/SalesInventory/Test/Unit/Observer/RefundOrderInventoryObserverTest.php
index 8bcd178bdded5d4d5beaf808860e94a69e366ca7..4e553493d07f63ed9f7d0a2d0d0ec7129d7580e7 100644
--- a/app/code/Magento/SalesInventory/Test/Unit/Observer/RefundOrderInventoryObserverTest.php
+++ b/app/code/Magento/SalesInventory/Test/Unit/Observer/RefundOrderInventoryObserverTest.php
@@ -68,7 +68,7 @@ class RefundOrderInventoryObserverTest extends \PHPUnit_Framework_TestCase
     /**
      * @var OrderInterface|\PHPUnit_Framework_MockObject_MockObject
      */
-    protected $orderMock;
+    private $orderMock;
 
     protected function setUp()
     {