diff --git a/src/Symfony/Component/Security/Guard/Firewall/GuardAuthenticationListener.php b/src/Symfony/Component/Security/Guard/Firewall/GuardAuthenticationListener.php
index 25de3ce440..94a1efb469 100644
--- a/src/Symfony/Component/Security/Guard/Firewall/GuardAuthenticationListener.php
+++ b/src/Symfony/Component/Security/Guard/Firewall/GuardAuthenticationListener.php
@@ -51,7 +51,7 @@ class GuardAuthenticationListener implements ListenerInterface
      * @param iterable|AuthenticatorInterface[] $guardAuthenticators   The authenticators, with keys that match what's passed to GuardAuthenticationProvider
      * @param LoggerInterface                   $logger                A LoggerInterface instance
      */
-    public function __construct(GuardAuthenticatorHandler $guardHandler, AuthenticationManagerInterface $authenticationManager, string $providerKey, $guardAuthenticators, LoggerInterface $logger = null)
+    public function __construct(GuardAuthenticatorHandler $guardHandler, AuthenticationManagerInterface $authenticationManager, string $providerKey, iterable $guardAuthenticators, LoggerInterface $logger = null)
     {
         if (empty($providerKey)) {
             throw new \InvalidArgumentException('$providerKey must not be empty.');
diff --git a/src/Symfony/Component/Security/Guard/Provider/GuardAuthenticationProvider.php b/src/Symfony/Component/Security/Guard/Provider/GuardAuthenticationProvider.php
index 625ac5e6fe..d4d23dfb0d 100644
--- a/src/Symfony/Component/Security/Guard/Provider/GuardAuthenticationProvider.php
+++ b/src/Symfony/Component/Security/Guard/Provider/GuardAuthenticationProvider.php
@@ -45,7 +45,7 @@ class GuardAuthenticationProvider implements AuthenticationProviderInterface
      * @param UserProviderInterface             $userProvider        The user provider
      * @param string                            $providerKey         The provider (i.e. firewall) key
      */
-    public function __construct($guardAuthenticators, UserProviderInterface $userProvider, string $providerKey, UserCheckerInterface $userChecker)
+    public function __construct(iterable $guardAuthenticators, UserProviderInterface $userProvider, string $providerKey, UserCheckerInterface $userChecker)
     {
         $this->guardAuthenticators = $guardAuthenticators;
         $this->userProvider = $userProvider;