diff --git a/security/user_provider.rst b/security/user_provider.rst
index 45f4911f762..bcdaf9e6e1f 100644
--- a/security/user_provider.rst
+++ b/security/user_provider.rst
@@ -123,7 +123,7 @@ the ``property`` config key. If you want a bit more control over this - e.g. you
 want to find a user by ``email`` *or* ``username``, you can do that by making
 your ``UserRepository`` implement the
 :class:`Symfony\\Bridge\\Doctrine\\Security\\User\\UserLoaderInterface`. This
-interface only requires one method: ``loadUserByUsername($username)``::
+interface only requires one method: ``loadUserByUsername(string $username)``::
 
     // src/Repository/UserRepository.php
     namespace App\Repository;
@@ -135,7 +135,7 @@ interface only requires one method: ``loadUserByUsername($username)``::
     {
         // ...
 
-        public function loadUserByUsername($usernameOrEmail)
+        public function loadUserByUsername(string $usernameOrEmail)
         {
             return $this->createQuery(
                     'SELECT u
@@ -366,7 +366,7 @@ command will generate a nice skeleton to get you started::
          *
          * @throws UsernameNotFoundException if the user is not found
          */
-        public function loadUserByUsername($username)
+        public function loadUserByUsername(string $username)
         {
             // Load a User object from your data source or throw UsernameNotFoundException.
             // The $username argument may not actually be a username:
@@ -402,7 +402,7 @@ command will generate a nice skeleton to get you started::
         /**
          * Tells Symfony to use this provider for this User class.
          */
-        public function supportsClass($class)
+        public function supportsClass(string $class)
         {
             return User::class === $class;
         }