diff --git a/src/Symfony/Component/Security/Guard/Provider/GuardAuthenticationProvider.php b/src/Symfony/Component/Security/Guard/Provider/GuardAuthenticationProvider.php
index 09e16a9fa4..e705b0f4c4 100644
--- a/src/Symfony/Component/Security/Guard/Provider/GuardAuthenticationProvider.php
+++ b/src/Symfony/Component/Security/Guard/Provider/GuardAuthenticationProvider.php
@@ -115,7 +115,7 @@ class GuardAuthenticationProvider implements AuthenticationProviderInterface
         $this->userChecker->checkPreAuth($user);
         if (true !== $checkCredentialsResult = $guardAuthenticator->checkCredentials($token->getCredentials(), $user)) {
             if (false !== $checkCredentialsResult) {
-                throw new \TypeError(sprintf('%s::checkCredentials() must return a boolean value.', \get_class($guardAuthenticator)));
+                throw new \TypeError(sprintf('"%s::checkCredentials()" must return a boolean value.', \get_class($guardAuthenticator)));
             }
 
             throw new BadCredentialsException(sprintf('Authentication failed because "%s::checkCredentials()" did not return true.', \get_class($guardAuthenticator)));