diff --git a/src/Symfony/Component/Security/Core/Authentication/Provider/LdapBindAuthenticationProvider.php b/src/Symfony/Component/Security/Core/Authentication/Provider/LdapBindAuthenticationProvider.php
index 9c07fd5a35697..aa2c4803f1a68 100644
--- a/src/Symfony/Component/Security/Core/Authentication/Provider/LdapBindAuthenticationProvider.php
+++ b/src/Symfony/Component/Security/Core/Authentication/Provider/LdapBindAuthenticationProvider.php
@@ -84,7 +84,7 @@ protected function checkAuthentication(UserInterface $user, UsernamePasswordToke
         $username = $token->getUsername();
         $password = $token->getCredentials();
 
-        if ('' === $password) {
+        if ('' === (string) $password) {
             throw new BadCredentialsException('The presented password must not be empty.');
         }
 
diff --git a/src/Symfony/Component/Security/Core/Tests/Authentication/Provider/LdapBindAuthenticationProviderTest.php b/src/Symfony/Component/Security/Core/Tests/Authentication/Provider/LdapBindAuthenticationProviderTest.php
index d65e8e7cc52e4..19f92528060bd 100644
--- a/src/Symfony/Component/Security/Core/Tests/Authentication/Provider/LdapBindAuthenticationProviderTest.php
+++ b/src/Symfony/Component/Security/Core/Tests/Authentication/Provider/LdapBindAuthenticationProviderTest.php
@@ -45,6 +45,23 @@ public function testEmptyPasswordShouldThrowAnException()
         $reflection->invoke($provider, new User('foo', null), new UsernamePasswordToken('foo', '', 'key'));
     }
 
+    /**
+     * @expectedException        \Symfony\Component\Security\Core\Exception\BadCredentialsException
+     * @expectedExceptionMessage The presented password must not be empty.
+     */
+    public function testNullPasswordShouldThrowAnException()
+    {
+        $userProvider = $this->getMockBuilder('Symfony\Component\Security\Core\User\UserProviderInterface')->getMock();
+        $ldap = $this->getMockBuilder('Symfony\Component\Ldap\LdapClientInterface')->getMock();
+        $userChecker = $this->getMockBuilder('Symfony\Component\Security\Core\User\UserCheckerInterface')->getMock();
+
+        $provider = new LdapBindAuthenticationProvider($userProvider, $userChecker, 'key', $ldap);
+        $reflection = new \ReflectionMethod($provider, 'checkAuthentication');
+        $reflection->setAccessible(true);
+
+        $reflection->invoke($provider, new User('foo', null), new UsernamePasswordToken('foo', null, 'key'));
+    }
+
     /**
      * @expectedException        \Symfony\Component\Security\Core\Exception\BadCredentialsException
      * @expectedExceptionMessage The presented password is invalid.