diff --git a/UPGRADE-3.3.md b/UPGRADE-3.3.md
index 2253bea93b..490415f1a5 100644
--- a/UPGRADE-3.3.md
+++ b/UPGRADE-3.3.md
@@ -113,6 +113,8 @@ SecurityBundle
  * `UserPasswordEncoderCommand::getContainer()` is deprecated, and this class won't
     extend `ContainerAwareCommand` nor implement `ContainerAwareInterface` anymore in 4.0.
 
+ * [BC BREAK] Keys of the `users` node for `in_memory` user provider are no longer normalized.
+
 Serializer
 ----------
 
diff --git a/src/Symfony/Bundle/SecurityBundle/CHANGELOG.md b/src/Symfony/Bundle/SecurityBundle/CHANGELOG.md
index 198aa92570..9691e5af03 100644
--- a/src/Symfony/Bundle/SecurityBundle/CHANGELOG.md
+++ b/src/Symfony/Bundle/SecurityBundle/CHANGELOG.md
@@ -9,6 +9,7 @@ CHANGELOG
  * Deprecated `UserPasswordEncoderCommand::getContainer()` and relying on the
   `ContainerAwareInterface` interface for this command.
  * Deprecated the `FirewallMap::$map` and `$container` properties.
+ * [BC BREAK] Keys of the `users` node for `in_memory` user provider are no longer normalized.
 
 3.2.0
 -----
diff --git a/src/Symfony/Bundle/SecurityBundle/DependencyInjection/Security/UserProvider/InMemoryFactory.php b/src/Symfony/Bundle/SecurityBundle/DependencyInjection/Security/UserProvider/InMemoryFactory.php
index b3752f4b18..f226b47cf5 100644
--- a/src/Symfony/Bundle/SecurityBundle/DependencyInjection/Security/UserProvider/InMemoryFactory.php
+++ b/src/Symfony/Bundle/SecurityBundle/DependencyInjection/Security/UserProvider/InMemoryFactory.php
@@ -52,6 +52,7 @@ class InMemoryFactory implements UserProviderFactoryInterface
             ->children()
                 ->arrayNode('users')
                     ->useAttributeAsKey('name')
+                    ->normalizeKeys(false)
                     ->prototype('array')
                         ->children()
                             ->scalarNode('password')->defaultValue(uniqid('', true))->end()