diff --git a/src/DependencyInjection/ExerciseHTMLPurifierExtension.php b/src/DependencyInjection/ExerciseHTMLPurifierExtension.php
index 8dd3fa37..061a4043 100644
--- a/src/DependencyInjection/ExerciseHTMLPurifierExtension.php
+++ b/src/DependencyInjection/ExerciseHTMLPurifierExtension.php
@@ -8,17 +8,17 @@
 use Exercise\HTMLPurifierBundle\HTMLPurifiersRegistryInterface;
 use Symfony\Component\Config\FileLocator;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
-use Symfony\Component\DependencyInjection\Loader\XmlFileLoader;
-use Symfony\Component\DependencyInjection\Reference;
 use Symfony\Component\DependencyInjection\Extension\Extension;
+use Symfony\Component\DependencyInjection\Loader\PhpFileLoader;
+use Symfony\Component\DependencyInjection\Reference;
 
 class ExerciseHTMLPurifierExtension extends Extension
 {
     public function load(array $configs, ContainerBuilder $container): void
     {
-        $loader = new XmlFileLoader($container, new FileLocator(__DIR__.'/../Resources/config'));
+        $loader = new PhpFileLoader($container, new FileLocator(__DIR__.'/../Resources/config'));
 
-        $loader->load('html_purifier.xml');
+        $loader->load('services.php');
 
         $configs = $this->processConfiguration(new Configuration(), $configs);
 
@@ -30,8 +30,6 @@ public function load(array $configs, ContainerBuilder $container): void
         }
 
         $serializerPaths = [];
-        // Drop when require Symfony > 3.4
-        $registerAlias = method_exists($container, 'registerAliasForArgument');
 
         foreach ($configs['html_profiles'] as $name => $definition) {
             $configId = "exercise_html_purifier.config.$name";
@@ -71,7 +69,7 @@ public function load(array $configs, ContainerBuilder $container): void
                 $serializerPaths[] = $definition['config']['Cache.SerializerPath'];
             }
 
-            if ($registerAlias && $default) {
+            if ($default) {
                 $container->registerAliasForArgument($id, \HTMLPurifier::class, "$name.purifier");
             }
         }
diff --git a/src/HTMLPurifierConfigFactory.php b/src/HTMLPurifierConfigFactory.php
index 6eac59fb..e8e88e4e 100644
--- a/src/HTMLPurifierConfigFactory.php
+++ b/src/HTMLPurifierConfigFactory.php
@@ -28,7 +28,7 @@ public static function create(
         array $parents = [],
         array $attributes = [],
         array $elements = [],
-        array $blankElements = []
+        array $blankElements = [],
     ): \HTMLPurifier_Config {
         if ($defaultConfig) {
             $config = \HTMLPurifier_Config::inherit($defaultConfig);
diff --git a/src/Resources/config/html_purifier.xml b/src/Resources/config/html_purifier.xml
deleted file mode 100644
index d3bfac09..00000000
--- a/src/Resources/config/html_purifier.xml
+++ /dev/null
@@ -1,28 +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>
-        <service id="exercise_html_purifier.cache_warmer.serializer" class="Exercise\HTMLPurifierBundle\CacheWarmer\SerializerCacheWarmer" public="false">
-            <argument /><!-- cache paths -->
-            <argument /><!-- profiles -->
-            <argument type="service" id="Exercise\HTMLPurifierBundle\HTMLPurifiersRegistryInterface" />
-            <argument type="service" id="filesystem" />
-            <tag name="kernel.cache_warmer" />
-        </service>
-
-        <service id="exercise_html_purifier.form.text_type_extension" class="Exercise\HTMLPurifierBundle\Form\TypeExtension\HTMLPurifierTextTypeExtension" public="false">
-            <argument type="service" id="Exercise\HTMLPurifierBundle\HTMLPurifiersRegistryInterface" />
-            <tag name="form.type_extension" extended-type="Symfony\Component\Form\Extension\Core\Type\TextType" />
-        </service>
-
-        <service id="exercise_html_purifier.twig.extension" class="Exercise\HTMLPurifierBundle\Twig\HTMLPurifierExtension" public="false">
-            <tag name="twig.extension" />
-        </service>
-
-        <service id="exercise_html_purifier.twig.runtime" class="Exercise\HTMLPurifierBundle\Twig\HTMLPurifierRuntime" public="false">
-            <argument type="service" id="Exercise\HTMLPurifierBundle\HTMLPurifiersRegistryInterface" />
-            <tag name="twig.runtime" />
-        </service>
-    </services>
-</container>
diff --git a/src/Resources/config/services.php b/src/Resources/config/services.php
new file mode 100644
index 00000000..dad69f2d
--- /dev/null
+++ b/src/Resources/config/services.php
@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Symfony\Component\DependencyInjection\Loader\Configurator;
+
+
+use Exercise\HTMLPurifierBundle\CacheWarmer\SerializerCacheWarmer;
+use Exercise\HTMLPurifierBundle\Form\TypeExtension\HTMLPurifierTextTypeExtension;
+use Exercise\HTMLPurifierBundle\HTMLPurifiersRegistryInterface;
+use Exercise\HTMLPurifierBundle\Twig\HTMLPurifierExtension;
+use Exercise\HTMLPurifierBundle\Twig\HTMLPurifierRuntime;
+use Symfony\Component\Form\Extension\Core\Type\TextType;
+
+return function (ContainerConfigurator $container): void {
+    $container->services()
+        ->set('exercise_html_purifier.cache_warmer.serializer', SerializerCacheWarmer::class)
+            ->tag('kernel.cache_warmer')
+            ->args([
+                abstract_arg('cache paths'),
+                abstract_arg('profiles'),
+                service(HTMLPurifiersRegistryInterface::class),
+                service('filesystem'),
+            ])
+
+        ->set('exercise_html_purifier.form.text_type_extension', HTMLPurifierTextTypeExtension::class)
+            ->tag('form.type_extension', ['extended_type' => TextType::class])
+            ->args([
+                service(HTMLPurifiersRegistryInterface::class),
+            ])
+
+        ->set('exercise_html_purifier.twig.extension', HTMLPurifierExtension::class)
+            ->tag('twig.extension')
+
+        ->set('exercise_html_purifier.twig.runtime', HTMLPurifierRuntime::class)
+            ->tag('twig.runtime')
+            ->args([
+                service(HTMLPurifiersRegistryInterface::class),
+            ]);
+};
diff --git a/tests/HTMLPurifierConfigFactoryTest.php b/tests/HTMLPurifierConfigFactoryTest.php
index 70dfec9c..ff780bfe 100644
--- a/tests/HTMLPurifierConfigFactoryTest.php
+++ b/tests/HTMLPurifierConfigFactoryTest.php
@@ -61,7 +61,7 @@ public static function buildHTMLDefinition(
         \HTMLPurifier_HTMLDefinition $def,
         array $attributes,
         array $elements,
-        array $blankElements
+        array $blankElements,
     ): void {
         ++self::$calledBuild;
         parent::buildHTMLDefinition($def, $attributes, $elements, $blankElements);