diff --git a/app/code/Magento/Robots/Test/Unit/Controller/Index/IndexTest.php b/app/code/Magento/Robots/Test/Unit/Controller/Index/IndexTest.php
index 22a69cc13bd523e8a73686960045c23d1eecfd3e..d3a7a97c7ea805952d35f5e9bcebee90a01eaab3 100644
--- a/app/code/Magento/Robots/Test/Unit/Controller/Index/IndexTest.php
+++ b/app/code/Magento/Robots/Test/Unit/Controller/Index/IndexTest.php
@@ -51,6 +51,9 @@ class IndexTest extends \PHPUnit\Framework\TestCase
         $resultPageMock->expects($this->once())
             ->method('addHandle')
             ->with('robots_index_index');
+        $resultPageMock->expects($this->once())
+            ->method('setHeader')
+            ->with('Content-Type', 'text/plain');
 
         $this->resultPageFactory->expects($this->any())
             ->method('create')