diff --git a/composer.json b/composer.json
index 3f42d95..cc15e12 100644
--- a/composer.json
+++ b/composer.json
@@ -12,11 +12,11 @@
     ],
     "require": {
         "php": ">=5.5.9",
-        "symfony/config": "~2.8|~3.0",
-        "symfony/dependency-injection": "~2.8|~3.0",
-        "symfony/http-kernel": "~2.8|~3.0",
-        "symfony/security-bundle": "~2.8|~3.0",
-        "symfony/security-core": "~2.8|~3.0"
+        "symfony/config": "~4.0|~5.0",
+        "symfony/dependency-injection": "~4.0|~5.0",
+        "symfony/http-kernel": "~4.0|~5.0",
+        "symfony/security-bundle": "~4.0|~5.0",
+        "symfony/security-core": "~4.0|~5.0"
     },
     "autoload": {
         "psr-4": {
diff --git a/src/DependencyInjection/Configuration.php b/src/DependencyInjection/Configuration.php
index 3d33269..3bcb035 100644
--- a/src/DependencyInjection/Configuration.php
+++ b/src/DependencyInjection/Configuration.php
@@ -22,8 +22,8 @@ class Configuration implements ConfigurationInterface
      */
     public function getConfigTreeBuilder()
     {
-        $treeBuilder = new TreeBuilder();
-        $treeBuilder->root('phpmentors_composite_password_authentication');
+        $treeBuilder = new TreeBuilder('phpmentors_composite_password_authentication');
+        $treeBuilder->getRootNode();
 
         return $treeBuilder;
     }
diff --git a/src/DependencyInjection/Security/Factory/FormLoginCompositePasswordFactory.php b/src/DependencyInjection/Security/Factory/FormLoginCompositePasswordFactory.php
index 879ebfa..f352e43 100644
--- a/src/DependencyInjection/Security/Factory/FormLoginCompositePasswordFactory.php
+++ b/src/DependencyInjection/Security/Factory/FormLoginCompositePasswordFactory.php
@@ -13,6 +13,7 @@
 namespace PHPMentors\CompositePasswordAuthenticationBundle\DependencyInjection\Security\Factory;
 
 use Symfony\Bundle\SecurityBundle\DependencyInjection\Security\Factory\FormLoginFactory;
+use Symfony\Component\DependencyInjection\ChildDefinition;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\DefinitionDecorator;
 use Symfony\Component\DependencyInjection\Reference;
@@ -22,7 +23,7 @@ class FormLoginCompositePasswordFactory extends FormLoginFactory
     /**
      * {@inheritdoc}
      */
-    public function getKey()
+    public function getKey(): string
     {
         return 'form-login-composite-password';
     }
@@ -30,11 +31,11 @@ public function getKey()
     /**
      * {@inheritdoc}
      */
-    protected function createAuthProvider(ContainerBuilder $container, $id, $config, $userProviderId)
+    protected function createAuthProvider(ContainerBuilder $container, string $id, array $config, string $userProviderId): string
     {
         $provider = 'phpmentors_composite_password_authentication.composite_password_dao_authentication_provider.'.$id;
         $container
-            ->setDefinition($provider, new DefinitionDecorator('phpmentors_composite_password_authentication.composite_password_dao_authentication_provider'))
+            ->setDefinition($provider, new ChildDefinition('phpmentors_composite_password_authentication.composite_password_dao_authentication_provider'))
             ->replaceArgument(0, new Reference($userProviderId))
             ->replaceArgument(1, new Reference('security.user_checker.'.$id))
             ->replaceArgument(2, $id)