diff --git a/composer.json b/composer.json
index 0cace9e..ba32f77 100644
--- a/composer.json
+++ b/composer.json
@@ -13,21 +13,21 @@
     "require": {
         "php": ">=5.3.9",
         "phpmentors/domain-kata": "~1.4",
-        "symfony/config": "~2.8|~3.0|~4.0",
-        "symfony/dependency-injection": "~2.8|~3.0|~4.0",
-        "symfony/framework-bundle": "~2.8|~3.0|~4.0",
-        "symfony/http-kernel": "~2.8|~3.0|~4.0",
-        "symfony/routing": "~2.8|~3.0|~4.0",
-        "symfony/templating": "~2.8|~3.0|~4.0"
+        "symfony/config": "~4.0|~5.0",
+        "symfony/dependency-injection": "~4.0|~5.0",
+        "symfony/framework-bundle": "~4.0|~5.0",
+        "symfony/http-kernel": "~4.0|~5.0",
+        "symfony/routing": "~4.0|~5.0",
+        "symfony/templating": "~4.0|~5.0"
     },
     "require-dev": {
         "phpunit/phpunit": "~4.0",
-        "symfony/asset": "~2.8|~3.0|~4.0",
-        "symfony/browser-kit": "~2.8|~3.0|~4.0",
-        "symfony/filesystem": "~2.8|~3.0|~4.0",
-        "symfony/http-foundation": "~2.8|~3.0|~4.0",
-        "symfony/twig-bridge": "~2.8|~3.0|~4.0",
-        "symfony/twig-bundle": "~2.8|~3.0|~4.0"
+        "symfony/asset": "~4.0|~5.0",
+        "symfony/browser-kit": "~4.0|~5.0",
+        "symfony/filesystem": "~4.0|~5.0",
+        "symfony/http-foundation": "~4.0|~5.0",
+        "symfony/twig-bridge": "~4.0|~5.0",
+        "symfony/twig-bundle": "~4.0|~5.0"
     },
     "autoload": {
         "psr-4": {
diff --git a/src/DependencyInjection/Configuration.php b/src/DependencyInjection/Configuration.php
index 175802f..30720f8 100644
--- a/src/DependencyInjection/Configuration.php
+++ b/src/DependencyInjection/Configuration.php
@@ -23,8 +23,8 @@ class Configuration implements ConfigurationInterface
      */
     public function getConfigTreeBuilder()
     {
-        $treeBuilder = new TreeBuilder();
-        $treeBuilder->root('phpmentors_proxy_url_rewrite')
+        $treeBuilder = new TreeBuilder('phpmentors_proxy_url_rewrite');
+        $treeBuilder->getRootNode()
             ->canBeEnabled()
             ->fixXmlConfig('proxy_url')
             ->children()
@@ -38,17 +38,6 @@ public function getConfigTreeBuilder()
                             ->scalarNode('proxy_url')
                                 ->isRequired()
                                 ->cannotBeEmpty()
-                                ->validate()
-                                    ->always(function ($v) {
-                                        try {
-                                            ProxyUrlFactory::parseUrl($v);
-                                        } catch (\UnexpectedValueException $e) {
-                                            throw new \InvalidArgumentException($e->getMessage());
-                                        }
-
-                                        return $v;
-                                    })
-                                ->end()
                             ->end()
                             ->scalarNode('proxy_host_filter_service')
                                 ->defaultNull()
diff --git a/src/DependencyInjection/PHPMentorsProxyURLRewriteExtension.php b/src/DependencyInjection/PHPMentorsProxyURLRewriteExtension.php
index fdfc83e..65eefa1 100644
--- a/src/DependencyInjection/PHPMentorsProxyURLRewriteExtension.php
+++ b/src/DependencyInjection/PHPMentorsProxyURLRewriteExtension.php
@@ -12,6 +12,7 @@
 
 namespace PHPMentors\ProxyURLRewriteBundle\DependencyInjection;
 
+use PHPMentors\ProxyURLRewriteBundle\ProxyUrl\ProxyUrlFactory;
 use Symfony\Component\Config\FileLocator;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Loader\XmlFileLoader;
@@ -49,6 +50,13 @@ private function transformConfigToContainer(array $config, ContainerBuilder $con
     {
         if ($config['enabled']) {
             foreach ($config['proxy_urls'] as $id => $proxyUrl) {
+
+                try{
+                    ProxyUrlFactory::parseUrl($proxyUrl['path']);
+                } catch (\UnexpectedValueException $e) {
+                    throw new \InvalidArgumentException($e->getMessage());
+                }
+
                 if (class_exists('Symfony\Component\DependencyInjection\ChildDefinition')) {
                     $definitionClass = 'Symfony\Component\DependencyInjection\ChildDefinition';
                 } else {
diff --git a/src/EventListener/ProxyUrlRewriteListener.php b/src/EventListener/ProxyUrlRewriteListener.php
index 197d10e..8c7ad5d 100644
--- a/src/EventListener/ProxyUrlRewriteListener.php
+++ b/src/EventListener/ProxyUrlRewriteListener.php
@@ -14,6 +14,7 @@
 
 use PHPMentors\ProxyURLRewriteBundle\ProxyUrl\ProxyUrlMatcher;
 use Symfony\Component\HttpKernel\Event\GetResponseEvent;
+use Symfony\Component\HttpKernel\Event\RequestEvent;
 use Symfony\Component\HttpKernel\HttpKernelInterface;
 use Symfony\Component\Routing\RouterInterface;
 
@@ -50,9 +51,9 @@ public function setRouter(RouterInterface $router)
     }
 
     /**
-     * @param GetResponseEvent $event
+     * @param RequestEvent $event
      */
-    public function onKernelRequest(GetResponseEvent $event)
+    public function onKernelRequest(RequestEvent $event)
     {
         if ($event->getRequestType() == HttpKernelInterface::MASTER_REQUEST) {
             $matchedProxyUrl = $this->proxyUrlMatcher->match($this->router->getContext()->getPathInfo());