diff --git a/composer.json b/composer.json
index dee3525..380593f 100644
--- a/composer.json
+++ b/composer.json
@@ -8,29 +8,23 @@
     },
 
     "require": {
-        "php": "^7.2|8.0.*|8.1.*|8.2.*|8.3.*",
+        "php": ">= 8.1",
         "ext-json": "*",
-        "psr/container": "^1.0",
+        "psr/container": "^1.0|^2.0",
         "psr/log": "^1.1|^2.0|^3.0",
-        "symfony/config": "^4.0|^5.0|^6.0|^7.0",
-        "symfony/console": "^4.0|^5.0|^6.0|^7.0",
-        "symfony/dependency-injection": "^4.2|^5.0|^6.0|^7.0",
-        "symfony/event-dispatcher": "^4.3|^5.0|^6.0|^7.0",
-        "symfony/event-dispatcher-contracts": "^1.0|^2.0|^3.0",
-        "symfony/http-foundation": "^5.3|^6.0|^7.0",
-        "symfony/http-kernel": "^4.0|^5.0|^6.0|^7.0",
-        "symfony/proxy-manager-bridge": "^4.0|^5.0|^6.0|^7.0",
-        "symfony/service-contracts": "^1.0|^2.0|^3.0",
-        "twig/twig": "^1.36|^2.6|^3.0"
+        "symfony/config": "^6.4|^7.0",
+        "symfony/console": "^6.4|^7.0",
+        "symfony/dependency-injection": "^6.4|^7.0",
+        "symfony/event-dispatcher": "^6.4|^7.0",
+        "symfony/event-dispatcher-contracts": "^2.5|^3.0",
+        "symfony/http-foundation": "^6.4|^7.0",
+        "symfony/http-kernel": "^6.4|^7.0",
+        "symfony/service-contracts": "^2.5|^3.0",
+        "twig/twig": "^2.13|^3.0"
     },
 
     "require-dev": {
-        "symfony/stopwatch": "^5.4|^6.0|^7.0"
-    },
-
-    "suggest": {
-        "symfony/stopwatch": "um zu messen, wie lange der Aufbau des NavigationTree dauert",
-        "ocramius/proxy-manager": "damit der NavigationTree wirklich lazy erzeugt wird"
+        "symfony/stopwatch": "^6.4|^7.0"
     },
 
     "config": {
diff --git a/src/DependencyInjection/WebfactoryNavigationExtension.php b/src/DependencyInjection/WebfactoryNavigationExtension.php
index 81bbaec..9e05778 100644
--- a/src/DependencyInjection/WebfactoryNavigationExtension.php
+++ b/src/DependencyInjection/WebfactoryNavigationExtension.php
@@ -11,13 +11,13 @@
 use Symfony\Component\Config\FileLocator;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Extension\Extension;
-use Symfony\Component\DependencyInjection\Loader\XmlFileLoader;
+use Symfony\Component\DependencyInjection\Loader\PhpFileLoader;
 
 class WebfactoryNavigationExtension extends Extension
 {
     public function load(array $configs, ContainerBuilder $container): void
     {
-        $loader = new XmlFileLoader($container, new FileLocator(__DIR__.'/../Resources/config'));
-        $loader->load('services.xml');
+        $loader = new PhpFileLoader($container, new FileLocator(__DIR__.'/../Resources/config'));
+        $loader->load('services.php');
     }
 }
diff --git a/src/Resources/config/services.php b/src/Resources/config/services.php
new file mode 100644
index 0000000..faec7f5
--- /dev/null
+++ b/src/Resources/config/services.php
@@ -0,0 +1,61 @@
+<?php
+
+namespace Symfony\Component\DependencyInjection\Loader\Configurator;
+
+return static function (ContainerConfigurator $container) {
+    $services = $container->services();
+
+    $services->defaults()
+        ->private()
+        ->autowire()
+        ->autoconfigure();
+
+    $services->set(\Webfactory\Bundle\NavigationBundle\Build\BuildDispatcher::class)
+        ->share(false);
+
+    $services->alias('webfactory_navigation.tree_factory.dispatcher', \Webfactory\Bundle\NavigationBundle\Build\BuildDispatcher::class)
+        ->public();
+
+    $services->set(\Webfactory\Bundle\NavigationBundle\Build\TreeFactory::class)
+        ->lazy()
+        ->args([
+            service('config_cache_factory'),
+            '%kernel.cache_dir%/webfactory_navigation/tree.php',
+            service(\Psr\Container\ContainerInterface::class),
+            service('event_dispatcher'),
+            service('logger')->nullOnInvalid(),
+            service('debug.stopwatch')->nullOnInvalid(),
+        ])
+        ->tag('monolog.logger', ['channel' => 'webfactory_navigation'])
+        ->tag('container.service_subscriber');
+
+    $services->alias('webfactory_navigation.tree_factory', \Webfactory\Bundle\NavigationBundle\Build\TreeFactory::class)
+        ->public();
+
+    $services->set(\Webfactory\Bundle\NavigationBundle\Tree\Tree::class)
+        ->lazy()
+        ->factory([service(\Webfactory\Bundle\NavigationBundle\Build\TreeFactory::class), 'getTree']);
+
+    $services->alias('webfactory_navigation.tree', \Webfactory\Bundle\NavigationBundle\Tree\Tree::class)
+        ->public();
+
+    $services->set(\Webfactory\Bundle\NavigationBundle\Event\ActiveNodeEventListener::class)
+        ->tag('kernel.event_listener', ['event' => 'webfactory_navigation.tree_initialized', 'method' => 'initializeTree']);
+
+    $services->alias('webfactory_navigation.event.active_node_event_listener', \Webfactory\Bundle\NavigationBundle\Event\ActiveNodeEventListener::class);
+
+    $services->set(\Webfactory\Bundle\NavigationBundle\Twig\NavigationExtension::class)
+        ->tag('twig.extension');
+
+    $services->alias('webfactory_navigation.twig_extension', \Webfactory\Bundle\NavigationBundle\Twig\NavigationExtension::class);
+
+    $services->set(\Webfactory\Bundle\NavigationBundle\Command\DumpTreeCommand::class)
+        ->tag('console.command');
+
+    $services->alias('webfactory_navigation.command.dump_tree_command', \Webfactory\Bundle\NavigationBundle\Command\DumpTreeCommand::class);
+
+    $services->set(\Webfactory\Bundle\NavigationBundle\Command\LookupNodeCommand::class)
+        ->tag('console.command');
+
+    $services->alias('webfactory_navigation.command.lookup_node_command', \Webfactory\Bundle\NavigationBundle\Command\LookupNodeCommand::class);
+};
diff --git a/src/Resources/config/services.xml b/src/Resources/config/services.xml
deleted file mode 100644
index 9f30640..0000000
--- a/src/Resources/config/services.xml
+++ /dev/null
@@ -1,49 +0,0 @@
-<?xml version="1.0" ?>
-
-<container xmlns="http://symfony.com/schema/dic/services"
-           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-           xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
-    <services>
-        <defaults autoconfigure="true" autowire="true" public="false" />
-
-        <service id="Webfactory\Bundle\NavigationBundle\Build\BuildDispatcher" shared="false"/>
-        <service id="webfactory_navigation.tree_factory.dispatcher" alias="Webfactory\Bundle\NavigationBundle\Build\BuildDispatcher" public="true" />
-
-        <service id="Webfactory\Bundle\NavigationBundle\Build\TreeFactory" lazy="true">
-            <argument type="service" id="config_cache_factory" />
-            <argument>%kernel.cache_dir%/webfactory_navigation/tree.php</argument>
-            <argument type="service" id="Psr\Container\ContainerInterface"/>
-            <argument type="service" id="event_dispatcher"/>
-            <argument type="service" id="logger" on-invalid="null"/>
-            <argument type="service" id="debug.stopwatch" on-invalid="null"/>
-            <tag name="monolog.logger" channel="webfactory_navigation"/>
-            <tag name="container.service_subscriber" />
-        </service>
-        <service id="webfactory_navigation.tree_factory" alias="Webfactory\Bundle\NavigationBundle\Build\TreeFactory" public="true" />
-
-        <service id="Webfactory\Bundle\NavigationBundle\Tree\Tree" lazy="true">
-            <factory service="Webfactory\Bundle\NavigationBundle\Build\TreeFactory" method="getTree" />
-        </service>
-        <service id="webfactory_navigation.tree" alias="Webfactory\Bundle\NavigationBundle\Tree\Tree" public="true" />
-
-        <service id="Webfactory\Bundle\NavigationBundle\Event\ActiveNodeEventListener">
-            <tag name="kernel.event_listener" event="webfactory_navigation.tree_initialized" method="initializeTree"/>
-        </service>
-        <service id="webfactory_navigation.event.active_node_event_listener" alias="Webfactory\Bundle\NavigationBundle\Event\ActiveNodeEventListener" />
-
-        <service id="Webfactory\Bundle\NavigationBundle\Twig\NavigationExtension">
-            <tag name="twig.extension"/>
-        </service>
-        <service id="webfactory_navigation.twig_extension" alias="Webfactory\Bundle\NavigationBundle\Twig\NavigationExtension" />
-
-        <service id="Webfactory\Bundle\NavigationBundle\Command\DumpTreeCommand">
-            <tag name="console.command"/>
-        </service>
-        <service id="webfactory_navigation.command.dump_tree_command" alias="Webfactory\Bundle\NavigationBundle\Command\DumpTreeCommand" />
-
-        <service id="Webfactory\Bundle\NavigationBundle\Command\LookupNodeCommand">
-            <tag name="console.command"/>
-        </service>
-        <service id="webfactory_navigation.command.lookup_node_command" alias="Webfactory\Bundle\NavigationBundle\Command\LookupNodeCommand" />
-    </services>
-</container>