diff --git a/tests/ResponseTest.php b/tests/ResponseTest.php
index 2f184347..61485057 100644
--- a/tests/ResponseTest.php
+++ b/tests/ResponseTest.php
@@ -263,7 +263,7 @@ public function invalidHeaderProvider()
         return [
             ['foo', [], 'Header value can not be an empty array.'],
             ['', '', 'Header name can not be empty.'],
-            ['foo', new \stdClass(),  'Header value must be scalar or null but stdClass provided.'],
+            ['foo', new \stdClass(), 'Header value must be scalar or null but stdClass provided.'],
         ];
     }