diff --git a/src/Symfony/Bundle/SecurityBundle/Tests/Functional/SwitchUserPreAuthenticatedTest.php b/src/Symfony/Bundle/SecurityBundle/Tests/Functional/SwitchUserPreAuthenticatedTest.php
new file mode 100644
index 0000000000000..0f60250379063
--- /dev/null
+++ b/src/Symfony/Bundle/SecurityBundle/Tests/Functional/SwitchUserPreAuthenticatedTest.php
@@ -0,0 +1,83 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Bundle\SecurityBundle\Tests\Functional;
+
+class SwitchUserPreAuthenticatedTest extends WebTestCase
+{
+    /**
+     * @dataProvider getTestParameters
+     */
+    public function testSwitchUser($originalUser, $targetUser, $expectedUser, $expectedStatus)
+    {
+        $client = $this->createAuthenticatedClient($originalUser);
+
+        $client->request('GET', '/profile?_switch_user='.$targetUser);
+
+        $this->assertEquals($expectedStatus, $client->getResponse()->getStatusCode());
+        $this->assertEquals($expectedUser, $client->getProfile()->getCollector('security')->getUser());
+    }
+
+    public function testSwitchedUserCannotSwitchToOther()
+    {
+        $client = $this->createAuthenticatedClient('user_can_switch');
+
+        $client->request('GET', '/profile?_switch_user=user_cannot_switch_1');
+        $client->request('GET', '/profile?_switch_user=user_cannot_switch_2');
+
+        $this->assertEquals(500, $client->getResponse()->getStatusCode());
+        $this->assertEquals('user_cannot_switch_1', $client->getProfile()->getCollector('security')->getUser());
+    }
+
+    public function testSwitchedUserExit()
+    {
+        $client = $this->createAuthenticatedClient('user_can_switch');
+
+        $client->request('GET', '/profile?_switch_user=user_cannot_switch_1');
+        $client->request('GET', '/profile?_switch_user=_exit');
+
+        $this->assertEquals(200, $client->getResponse()->getStatusCode());
+        $this->assertEquals('user_can_switch', $client->getProfile()->getCollector('security')->getUser());
+    }
+
+    public function getTestParameters()
+    {
+        return array(
+            'unauthorized_user_cannot_switch' => array('user_cannot_switch_1', 'user_cannot_switch_1', 'user_cannot_switch_1', 403),
+            'authorized_user_can_switch' => array('user_can_switch', 'user_cannot_switch_1', 'user_cannot_switch_1', 200),
+            'authorized_user_cannot_switch_to_non_existent' => array('user_can_switch', 'user_does_not_exist', 'user_can_switch', 500),
+            'authorized_user_can_switch_to_himself' => array('user_can_switch', 'user_can_switch', 'user_can_switch', 200),
+        );
+    }
+
+    protected function createAuthenticatedClient($username)
+    {       
+        $client = $this->createClient(array('test_case' => 'StandardFormLogin', 'root_config' => 'switchuser_preauthenticated.yml'));
+        $client->followRedirects(true);
+
+        $client->setServerParameters(array(
+            'SSL_CLIENT_S_DN_Email' => $username,
+            'SSL_CLIENT_S_DN' => 'test',
+        ));
+
+        return $client;
+    }
+
+    public static function setUpBeforeClass()
+    {
+        parent::deleteTmpDir('StandardFormLogin');
+    }
+
+    public static function tearDownAfterClass()
+    {
+        parent::deleteTmpDir('StandardFormLogin');
+    }
+}
diff --git a/src/Symfony/Bundle/SecurityBundle/Tests/Functional/app/StandardFormLogin/switchuser_preauthenticated.yml b/src/Symfony/Bundle/SecurityBundle/Tests/Functional/app/StandardFormLogin/switchuser_preauthenticated.yml
new file mode 100644
index 0000000000000..e87fd3c3823aa
--- /dev/null
+++ b/src/Symfony/Bundle/SecurityBundle/Tests/Functional/app/StandardFormLogin/switchuser_preauthenticated.yml
@@ -0,0 +1,16 @@
+imports:
+    - { resource: ./config.yml }
+
+security:
+    providers:
+        in_memory:
+            memory:
+                users:
+                    user_can_switch:      { password: test, roles: [ROLE_USER, ROLE_ALLOWED_TO_SWITCH] }
+                    user_cannot_switch_1: { password: test, roles: [ROLE_USER] }
+                    user_cannot_switch_2: { password: test, roles: [ROLE_USER] }
+    firewalls:
+        default:
+            switch_user: true
+            form_login: false
+            x509: true
diff --git a/src/Symfony/Component/Security/Http/Firewall/AbstractPreAuthenticatedListener.php b/src/Symfony/Component/Security/Http/Firewall/AbstractPreAuthenticatedListener.php
index b793310d9b336..bdccff9d2ae61 100644
--- a/src/Symfony/Component/Security/Http/Firewall/AbstractPreAuthenticatedListener.php
+++ b/src/Symfony/Component/Security/Http/Firewall/AbstractPreAuthenticatedListener.php
@@ -54,6 +54,15 @@ public function __construct(TokenStorageInterface $tokenStorage, AuthenticationM
      */
     final public function handle(GetResponseEvent $event)
     {
+        $token = $this->tokenStorage->getToken();
+        if (null !== $token && !$token instanceof PreAuthenticatedToken && $token->isAuthenticated()) {
+            if (null !== $this->logger) {
+                $this->logger->debug('An authenticated token is already provided, bypass PreAuthenticatedListener.', array('token' => (string) $token));
+            }
+
+            return;
+        }
+
         $request = $event->getRequest();
 
         try {
@@ -65,10 +74,10 @@ final public function handle(GetResponseEvent $event)
         }
 
         if (null !== $this->logger) {
-            $this->logger->debug('Checking current security token.', array('token' => (string) $this->tokenStorage->getToken()));
+            $this->logger->debug('Checking current security token.', array('token' => (string) $token));
         }
 
-        if (null !== $token = $this->tokenStorage->getToken()) {
+        if (null !== $token) {
             if ($token instanceof PreAuthenticatedToken && $this->providerKey == $token->getProviderKey() && $token->isAuthenticated() && $token->getUsername() === $user) {
                 return;
             }