diff --git a/3-multi/src/Controller.php b/3-multi/src/Controller.php
index 47d86a2..fe5569f 100644
--- a/3-multi/src/Controller.php
+++ b/3-multi/src/Controller.php
@@ -41,6 +41,6 @@ public function index()
         $response->getBody()->write(json_encode($this->profiles));
 
         return $response
-            ->withHeader('Content-type', 'application/json');
+            ->withHeader('Content-Type', 'application/json');
     }
 }