diff --git a/Tests/EventListener/MimeTypeListenerTest.php b/Tests/EventListener/MimeTypeListenerTest.php
index ba2e7097f..c43e81104 100644
--- a/Tests/EventListener/MimeTypeListenerTest.php
+++ b/Tests/EventListener/MimeTypeListenerTest.php
@@ -55,6 +55,8 @@ public function testOnKernelRequestNoZone()
         $listener = new MimeTypeListener(['soap' => ['application/soap+xml']]);
 
         $request = new Request();
+        $mimeType = $request->getMimeType('soap');
+
         $request->attributes->set(FOSRestBundle::ZONE_ATTRIBUTE, false);
         $event = $this->getMockBuilder(RequestEvent::class)
             ->disableOriginalConstructor()->getMock();
@@ -68,7 +70,7 @@ public function testOnKernelRequestNoZone()
 
         $listener->onKernelRequest($event);
 
-        $this->assertNull($request->getMimeType('soap'));
+        $this->assertSame($mimeType, $request->getMimeType('soap'));
     }
 
     public function testOnKernelRequestWithZone()