diff --git a/Firewall/SimpleFormAuthenticationListener.php b/Firewall/SimpleFormAuthenticationListener.php
index a8ccee0f..3d1895f4 100644
--- a/Firewall/SimpleFormAuthenticationListener.php
+++ b/Firewall/SimpleFormAuthenticationListener.php
@@ -97,7 +97,7 @@ protected function attemptAuthentication(Request $request)
             $password = ParameterBagUtils::getRequestParameterValue($request, $this->options['password_parameter']);
         }
 
-        if (!\is_string($username) && (!\is_object($username) || !\method_exists($username, '__toString'))) {
+        if (!\is_string($username) && (!\is_object($username) || !method_exists($username, '__toString'))) {
             throw new BadRequestHttpException(sprintf('The key "%s" must be a string, "%s" given.', $this->options['username_parameter'], \gettype($username)));
         }
 
diff --git a/Firewall/UsernamePasswordFormAuthenticationListener.php b/Firewall/UsernamePasswordFormAuthenticationListener.php
index 2b8ab8d0..e466698a 100644
--- a/Firewall/UsernamePasswordFormAuthenticationListener.php
+++ b/Firewall/UsernamePasswordFormAuthenticationListener.php
@@ -85,7 +85,7 @@ protected function attemptAuthentication(Request $request)
             $password = ParameterBagUtils::getRequestParameterValue($request, $this->options['password_parameter']);
         }
 
-        if (!\is_string($username) && (!\is_object($username) || !\method_exists($username, '__toString'))) {
+        if (!\is_string($username) && (!\is_object($username) || !method_exists($username, '__toString'))) {
             throw new BadRequestHttpException(sprintf('The key "%s" must be a string, "%s" given.', $this->options['username_parameter'], \gettype($username)));
         }