diff --git a/src/Bundle/Form/Extension/HttpFoundation/HttpFoundationRequestHandler.php b/src/Bundle/Form/Extension/HttpFoundation/HttpFoundationRequestHandler.php
index 592f5524c..a84479926 100644
--- a/src/Bundle/Form/Extension/HttpFoundation/HttpFoundationRequestHandler.php
+++ b/src/Bundle/Form/Extension/HttpFoundation/HttpFoundationRequestHandler.php
@@ -107,7 +107,7 @@ public function handleRequest(FormInterface $form, $request = null)
         $form->submit($data, 'PATCH' !== $method);
     }
 
-    public function isFileUpload($data)
+    public function isFileUpload($data): bool
     {
         return $data instanceof File;
     }