diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 861ea29..c9edde7 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -17,7 +17,7 @@ jobs:
         strategy:
             matrix:
                 php-version:
-                    - '8.2'
+                    - '8.4'
 
         steps:
             -
@@ -46,7 +46,7 @@ jobs:
 
             -
                 name: 'Install dependencies'
-                run: 'composer install --no-progress'
+                run: 'composer update --no-progress --prefer-stable'
 
             -
                 name: 'Check the code style'
@@ -60,7 +60,7 @@ jobs:
         strategy:
             matrix:
                 php-version:
-                    - '8.2'
+                    - '8.4'
 
         steps:
             -
@@ -89,7 +89,7 @@ jobs:
 
             -
                 name: 'Install dependencies'
-                run: 'composer install --no-progress'
+                run: 'composer update --no-progress --prefer-stable'
 
             -
                 name: 'Run PhpStan'
@@ -104,18 +104,9 @@ jobs:
             matrix:
                 include:
                     -
-                        php-version: '8.2'
+                        php-version: '8.4'
                         composer-options: '--prefer-stable'
-                        symfony-version: '6.3'
-                    -
-                        php-version: '8.2'
-                        composer-options: '--prefer-stable'
-                        symfony-version: '^6.4'
-
-                    -
-                        php-version: '8.2'
-                        composer-options: '--prefer-stable'
-                        symfony-version: '^7.0'
+                        symfony-version: '^8.0'
 
         steps:
             -
@@ -154,4 +145,5 @@ jobs:
 
             -
                 name: 'Run tests'
-                run: make phpunit
+                run: |
+                    vendor/bin/phpunit
diff --git a/.gitignore b/.gitignore
index e2245b8..0e3ff13 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,7 +2,6 @@ composer.lock
 /vendor/
 
 phpunit.xml
-.phpunit.result.cache
 .phpunit.cache/
 .phpunit
 
diff --git a/README.md b/README.md
index af9f33e..4c94301 100644
--- a/README.md
+++ b/README.md
@@ -27,7 +27,13 @@ Otherwise enable the `Rollerworks\Bundle\PasswordStrengthBundle\RollerworksPassw
 
 ## Requirements
 
-You need at least PHP PHP 8.2, mbstring is recommended but not required, and at least Symfony 6.
+You need at least PHP PHP 8.4 and Symfony 8, mbstring is recommended but not required.
+
+> [!NOTE]  
+> 
+> This package requires PHP 8.4 or higher and Symfony 8 or higher.
+> 
+> If you need support for older Symfony versions, use the [3.x branch](https://github.com/rollerworks/PasswordStrengthBundle/tree/3.x).
 
 ## Basic Usage
 
diff --git a/UPGRADE.md b/UPGRADE.md
index 0859915..9033437 100644
--- a/UPGRADE.md
+++ b/UPGRADE.md
@@ -1,6 +1,13 @@
 UPGRADE
 =======
 
+From 3.x to 4.0
+---------------
+
+* Support for Symfony 6 and 7 was removed, PHP 8.4 and Symfony 8.0 is now the minimum required version.
+
+* The constructor of password constraints has changed, see (Upgrade instructions of the validator library)[https://github.com/rollerworks/PasswordStrengthValidator/blob/main/UPGRADE.md]
+
 From 2.x to 3.0
 ---------------
 
diff --git a/composer.json b/composer.json
index 898dbb8..335cf4f 100644
--- a/composer.json
+++ b/composer.json
@@ -20,15 +20,15 @@
         }
     ],
     "require": {
-        "php": ">=8.2",
-        "rollerworks/password-strength-validator": "^2.0",
-        "symfony/framework-bundle": "^6.0 || ^7.0"
+        "php": ">=8.4",
+        "rollerworks/password-strength-validator": "^3.0",
+        "symfony/framework-bundle": "^8.0"
     },
     "require-dev": {
-        "matthiasnoback/symfony-dependency-injection-test": "^5.0 || ^v4.3.1",
-        "phpunit/phpunit": "^9.5",
+        "matthiasnoback/symfony-dependency-injection-test": "^6.2",
+        "phpunit/phpunit": "^12.4",
         "rollerscapes/standards": "^1.0",
-        "symfony/phpunit-bridge": "^6.0 || ^7.0"
+        "symfony/phpunit-bridge": "^8.0"
     },
     "minimum-stability": "dev",
     "prefer-stable": true,
@@ -52,7 +52,7 @@
     },
     "extra": {
         "branch-alias": {
-            "dev-main": "3.0-dev"
+            "dev-main": "4.0-dev"
         }
     }
 }
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index c7d9fc8..d34ab47 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,13 +1,14 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
+<!-- https://phpunit.de/manual/current/en/appendixes.configuration.html -->
 <phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.5/phpunit.xsd"
-         backupGlobals="false"
-         colors="true"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/12.4/phpunit.xsd"
          bootstrap="vendor/autoload.php"
-         beStrictAboutTestsThatDoNotTestAnything="false"
          beStrictAboutOutputDuringTests="true"
-         beStrictAboutTodoAnnotatedTests="true"
+         displayDetailsOnTestsThatTriggerWarnings="true"
+         failOnWarning="true"
+         colors="true"
+         cacheDirectory=".phpunit.cache"
 >
     <php>
         <ini name="error_reporting" value="-1"/>
@@ -16,6 +17,8 @@
         <ini name="intl.error_level" value="0"/>
         <ini name="memory_limit" value="-1"/>
         <ini name="default_charset" value="UTF-8"/>
+
+        <env name="SYMFONY_DEPRECATIONS_HELPER" value="max[self]=0" />
     </php>
 
     <testsuites>
@@ -24,13 +27,16 @@
         </testsuite>
     </testsuites>
 
-    <coverage>
+    <coverage />
+
+    <source>
         <include>
-            <directory>./src</directory>
+            <directory>src/</directory>
         </include>
         <exclude>
-            <directory>./vendor/</directory>
-            <directory>./tests/</directory>
+            <directory>src/Resources/</directory>
+            <directory>vendor/</directory>
+            <directory>tests/</directory>
         </exclude>
-    </coverage>
+    </source>
 </phpunit>
diff --git a/src/DependencyInjection/RollerworksPasswordStrengthExtension.php b/src/DependencyInjection/RollerworksPasswordStrengthExtension.php
index 5e93adb..bc6d3b0 100644
--- a/src/DependencyInjection/RollerworksPasswordStrengthExtension.php
+++ b/src/DependencyInjection/RollerworksPasswordStrengthExtension.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the RollerworksPasswordStrengthBundle package.
  *
@@ -16,14 +18,14 @@
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Extension\Extension;
 use Symfony\Component\DependencyInjection\Extension\PrependExtensionInterface;
-use Symfony\Component\DependencyInjection\Loader;
+use Symfony\Component\DependencyInjection\Loader\PhpFileLoader;
 
 final class RollerworksPasswordStrengthExtension extends Extension implements PrependExtensionInterface
 {
     public function load(array $configs, ContainerBuilder $container): void
     {
-        $loader = new Loader\XmlFileLoader($container, new FileLocator(__DIR__ . '/../Resources/config'));
-        $loader->load('strength_validator.xml');
+        $loader = new PhpFileLoader($container, new FileLocator(__DIR__ . '/../Resources/config'));
+        $loader->load('strength_validator.php');
     }
 
     public function prepend(ContainerBuilder $container): void
diff --git a/src/Resources/config/strength_validator.php b/src/Resources/config/strength_validator.php
new file mode 100644
index 0000000..39157f9
--- /dev/null
+++ b/src/Resources/config/strength_validator.php
@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the RollerworksPasswordStrengthBundle package.
+ *
+ * (c) Sebastiaan Stok <s.stok@rollerscapes.net>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+use Rollerworks\Component\PasswordStrength\Validator\Constraints\PasswordStrengthValidator;
+use Symfony\Component\DependencyInjection\Loader\Configurator\ContainerConfigurator;
+use function Symfony\Component\DependencyInjection\Loader\Configurator\service;
+
+return static function (ContainerConfigurator $container): void {
+    $di = $container->services();
+
+    $di->set(PasswordStrengthValidator::class)
+        ->args([service('translator')->nullOnInvalid()])
+        ->tag('validator.constraint_validator');
+};
diff --git a/src/Resources/config/strength_validator.xml b/src/Resources/config/strength_validator.xml
deleted file mode 100644
index ab4be5e..0000000
--- a/src/Resources/config/strength_validator.xml
+++ /dev/null
@@ -1,18 +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="Rollerworks\Component\PasswordStrength\Validator\Constraints\PasswordStrengthValidator">
-            <argument id="translator" type="service" on-invalid="null" />
-            <tag name="validator.constraint_validator" />
-        </service>
-
-        <service class="Rollerworks\Component\PasswordStrength\Validator\Constraints\PasswordStrengthValidator" id="rollerworks_password_strength.validator.password_strength.library">
-            <argument id="translator" type="service" on-invalid="null" />
-            <tag name="validator.constraint_validator" />
-        </service>
-    </services>
-</container>
diff --git a/src/RollerworksPasswordStrengthBundle.php b/src/RollerworksPasswordStrengthBundle.php
index ed93971..5da22de 100644
--- a/src/RollerworksPasswordStrengthBundle.php
+++ b/src/RollerworksPasswordStrengthBundle.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the RollerworksPasswordStrengthBundle package.
  *
@@ -13,4 +15,6 @@
 
 use Symfony\Component\HttpKernel\Bundle\Bundle;
 
-final class RollerworksPasswordStrengthBundle extends Bundle {}
+final class RollerworksPasswordStrengthBundle extends Bundle
+{
+}
diff --git a/tests/DependencyInjection/ExtensionTest.php b/tests/DependencyInjection/ExtensionTest.php
index 90693ce..5f8927e 100644
--- a/tests/DependencyInjection/ExtensionTest.php
+++ b/tests/DependencyInjection/ExtensionTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the RollerworksPasswordStrengthBundle package.
  *
@@ -19,7 +21,10 @@
 use Symfony\Component\Validator\ContainerConstraintValidatorFactory;
 use Symfony\Component\Validator\DependencyInjection\AddConstraintValidatorsPass;
 
-class ExtensionTest extends AbstractExtensionTestCase
+/**
+ * @internal
+ */
+final class ExtensionTest extends AbstractExtensionTestCase
 {
     public function test_password_validators_are_registered()
     {
@@ -34,7 +39,7 @@ public function test_password_validators_are_registered()
         /** @var ContainerConstraintValidatorFactory $factory */
         $factory = $this->container->get('validator.validator_factory');
 
-        self::assertInstanceOf(PasswordStrengthValidator::class, $factory->getInstance(new PasswordStrength(['minStrength' => 1])));
+        self::assertInstanceOf(PasswordStrengthValidator::class, $factory->getInstance(new PasswordStrength(minStrength: 1)));
     }
 
     protected function getContainerExtensions(): array