diff --git a/app/code/Magento/Robots/Controller/Index/Index.php b/app/code/Magento/Robots/Controller/Index/Index.php
index b94626e93432d5ebbef2af7f34db8fa3524c02b1..679066d723dce9f9c2bff40178d56f7d27d7a447 100644
--- a/app/code/Magento/Robots/Controller/Index/Index.php
+++ b/app/code/Magento/Robots/Controller/Index/Index.php
@@ -43,6 +43,7 @@ class Index extends Action
         /** @var Page $resultPage */
         $resultPage = $this->resultPageFactory->create(true);
         $resultPage->addHandle('robots_index_index');
+        $resultPage->setHeader('Content-Type', 'text/plain');
         return $resultPage;
     }
 }