diff --git a/src/Symfony/Component/Security/Core/User/User.php b/src/Symfony/Component/Security/Core/User/User.php
index a24cb69668..19f9c3e8c7 100644
--- a/src/Symfony/Component/Security/Core/User/User.php
+++ b/src/Symfony/Component/Security/Core/User/User.php
@@ -120,7 +120,7 @@ final class User implements UserInterface, EquatableInterface, AdvancedUserInter
     {
     }
 
-    public function getExtraFields()
+    public function getExtraFields(): array
     {
         return $this->extraFields;
     }