diff --git a/.php-cs-fixer.php b/.php-cs-fixer.php
index d5ef888..2b834e8 100644
--- a/.php-cs-fixer.php
+++ b/.php-cs-fixer.php
@@ -34,8 +34,5 @@
         'simplified_null_return' => false,
         'void_return' => true,
         'yoda_style' => [],
-
-        // @see https://github.com/FriendsOfPHP/PHP-CS-Fixer/issues/5495
-        'binary_operator_spaces' => ['operators' => ['|' => null]]
     ])
 ;
diff --git a/Builders/FormTreeBuilder.php b/Builders/FormTreeBuilder.php
index 722c60c..da282fc 100644
--- a/Builders/FormTreeBuilder.php
+++ b/Builders/FormTreeBuilder.php
@@ -23,6 +23,8 @@ class FormTreeBuilder
 {
     /**
      * Form type with no children labels
+     *
+     * @var array<string> $noChildren
      */
     private array $noChildren = ['date', 'time', 'datetime', 'choice'];
 
@@ -47,7 +49,7 @@ public function getTree(FormView $view): FormTree
     /**
      * Set form type that should not be treated as having children
      *
-     * @param array $types An array of types
+     * @param array<string> $types An array of types
      */
     public function setNoChildren(array $types): void
     {
diff --git a/DependencyInjection/Configuration.php b/DependencyInjection/Configuration.php
index df365d5..6261b6d 100644
--- a/DependencyInjection/Configuration.php
+++ b/DependencyInjection/Configuration.php
@@ -106,12 +106,11 @@ public function getConfigTreeBuilder(): TreeBuilder
     /**
      * Add Keys Config
      *
-     * @param string $key
-     * @param array  $default
+     * @param array<string,string>  $default
      *
      * @return ArrayNodeDefinition|NodeDefinition
      */
-    public function addKeysConfig($key, $default = [])
+    public function addKeysConfig(string $key, array $default = [])
     {
         $treeBuilder = new TreeBuilder($key);
         $node = $treeBuilder->getRootNode();
diff --git a/DependencyInjection/ElaoFormTranslationExtension.php b/DependencyInjection/ElaoFormTranslationExtension.php
index c2af423..2d7b125 100644
--- a/DependencyInjection/ElaoFormTranslationExtension.php
+++ b/DependencyInjection/ElaoFormTranslationExtension.php
@@ -47,7 +47,7 @@ public function load(array $configs, ContainerBuilder $container): void
      *
      * @param ContainerBuilder $container The container builder
      * @param LoaderInterface  $loader    The loader
-     * @param array            $config    An array of config keys
+     * @param array<string,mixed> $config    An array of config keys
      */
     private function loadTreeConfig(ContainerBuilder $container, LoaderInterface $loader, array $config): void
     {
diff --git a/Form/Extension/ButtonTypeExtension.php b/Form/Extension/ButtonTypeExtension.php
index 6780038..0e1dd2f 100644
--- a/Form/Extension/ButtonTypeExtension.php
+++ b/Form/Extension/ButtonTypeExtension.php
@@ -26,14 +26,6 @@ public static function getExtendedTypes(): iterable
         return [ButtonType::class];
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function getExtendedType()
-    {
-        return self::getExtendedTypes()[0];
-    }
-
     /**
      * {@inheritdoc}
      */
diff --git a/Form/Extension/ChoiceTypeExtension.php b/Form/Extension/ChoiceTypeExtension.php
index 5d4dd38..46da940 100644
--- a/Form/Extension/ChoiceTypeExtension.php
+++ b/Form/Extension/ChoiceTypeExtension.php
@@ -26,14 +26,6 @@ public static function getExtendedTypes(): iterable
         return [ChoiceType::class];
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function getExtendedType()
-    {
-        return self::getExtendedTypes()[0];
-    }
-
     /**
      * {@inheritdoc}
      */
diff --git a/Form/Extension/CollectionTypeExtension.php b/Form/Extension/CollectionTypeExtension.php
index b2ae0b9..c685d87 100644
--- a/Form/Extension/CollectionTypeExtension.php
+++ b/Form/Extension/CollectionTypeExtension.php
@@ -28,14 +28,6 @@ public static function getExtendedTypes(): iterable
         return [CollectionType::class];
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function getExtendedType()
-    {
-        return self::getExtendedTypes()[0];
-    }
-
     /**
      * {@inheritdoc}
      */
diff --git a/Form/Extension/FormTypeExtension.php b/Form/Extension/FormTypeExtension.php
index eb79acb..a491f51 100644
--- a/Form/Extension/FormTypeExtension.php
+++ b/Form/Extension/FormTypeExtension.php
@@ -26,14 +26,6 @@ public static function getExtendedTypes(): iterable
         return [FormType::class];
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function getExtendedType()
-    {
-        return self::getExtendedTypes()[0];
-    }
-
     /**
      * {@inheritdoc}
      */
diff --git a/Form/Extension/TreeAwareExtension.php b/Form/Extension/TreeAwareExtension.php
index d85edae..46c3d4b 100644
--- a/Form/Extension/TreeAwareExtension.php
+++ b/Form/Extension/TreeAwareExtension.php
@@ -35,6 +35,8 @@ abstract class TreeAwareExtension extends AbstractTypeExtension
 
     /**
      * Buildable keys list
+     *
+     * @var array<string,string>
      */
     protected array $keys;
 
@@ -67,7 +69,7 @@ public function setAutoGenerate(bool $enabled): void
      *
      * @param FormTreeBuilder $treeBuilder The FormKeyBuilder
      */
-    public function setTreeBuilder(FormTreeBuilder $treeBuilder = null): void
+    public function setTreeBuilder(FormTreeBuilder $treeBuilder): void
     {
         $this->treeBuilder = $treeBuilder;
     }
@@ -77,7 +79,7 @@ public function setTreeBuilder(FormTreeBuilder $treeBuilder = null): void
      *
      * @param FormKeyBuilder $keyBuilder The FormKeyBuilder
      */
-    public function setKeyBuilder(FormKeyBuilder $keyBuilder = null): void
+    public function setKeyBuilder(FormKeyBuilder $keyBuilder): void
     {
         $this->keyBuilder = $keyBuilder;
     }
@@ -85,7 +87,7 @@ public function setKeyBuilder(FormKeyBuilder $keyBuilder = null): void
     /**
      * Set buildable keys
      *
-     * @param array $keys Array of keys
+     * @param array<string,string> $keys Array of keys
      */
     public function setKeys(array $keys): void
     {
@@ -132,7 +134,10 @@ protected function generateKey(FormView &$view, $key, $value): void
         $this->setVar($view->vars, $key, $this->keyBuilder->buildKeyFromTree($view->vars['tree'], $value));
     }
 
-    protected function setVar(array &$vars, string $key, $value): void
+    /**
+     * @param array<string,mixed> &$vars
+     */
+    protected function setVar(array &$vars, string $key, mixed $value): void
     {
         if ($this->getPropertyAccessor()->isWritable($vars, $key)) {
             $this->getPropertyAccessor()->setValue($vars, $key, $value);
@@ -141,7 +146,10 @@ protected function setVar(array &$vars, string $key, $value): void
         }
     }
 
-    protected function optionEquals(array $options, string $key, $value): bool
+    /**
+     * @param array<string,mixed> $options
+     */
+    protected function optionEquals(array $options, string $key, mixed $value): bool
     {
         if ($this->getPropertyAccessor()->isReadable($options, $key)) {
             return $this->getPropertyAccessor()->getValue($options, $key) === $value;
diff --git a/Makefile b/Makefile
index d6f34e8..94a8061 100644
--- a/Makefile
+++ b/Makefile
@@ -1,11 +1,30 @@
-.PHONY: test
-
-PHP_CS_FIXER_VERSION=v3.10.0
+.SILENT:
+.PHONY: test build
 
 ###########
 # Helpers #
 ###########
 
+## Colors
+COLOR_RESET   = \033[0m
+COLOR_INFO    = \033[32m
+COLOR_COMMENT = \033[33m
+
+## Help
+help:
+	printf "${COLOR_COMMENT}Usage:${COLOR_RESET}\n"
+	printf " make [target]\n\n"
+	printf "${COLOR_COMMENT}Available targets:${COLOR_RESET}\n"
+	awk '/^[a-zA-Z\-\_0-9\.@]+:/ { \
+		helpMessage = match(lastLine, /^## (.*)/); \
+		if (helpMessage) { \
+			helpCommand = substr($$1, 0, index($$1, ":")); \
+			helpMessage = substr(lastLine, RSTART + 3, RLENGTH); \
+			printf " ${COLOR_INFO}%-16s${COLOR_RESET} %s\n", helpCommand, helpMessage; \
+		} \
+	} \
+	{ lastLine = $$0 }' $(MAKEFILE_LIST)
+
 define message_error
 	printf "$(COLOR_ERROR)(╯°□°)╯︵ ┻━┻ $(strip $(1))$(COLOR_RESET)\n"
 endef
@@ -13,39 +32,51 @@ endef
 php8:
 	@php -r "exit (PHP_MAJOR_VERSION == 8 ? 0 : 1);" || ($(call message_error, Please use PHP 8) && exit 1)
 
+###########
+# Install #
+###########
+
+## Install application
+install:
+	# Composer
+	composer install --verbose
+
+############
+# Security #
+############
+
+## Run security checks
+security:
+	symfony check:security
+
+security@test: export APP_ENV = test
+security@test: security
+
 ########
 # Lint #
 ########
 
-lint: lint-phpcsfixer lint-phpstan lint-composer
+## Run linters
+lint: lint.phpcsfixer lint.phpstan lint.composer
 
-lint-composer:
+lint.composer:
 	composer validate --strict
 
-php-cs-fixer.phar:
-	wget --no-verbose https://github.com/FriendsOfPHP/PHP-CS-Fixer/releases/download/${PHP_CS_FIXER_VERSION}/php-cs-fixer.phar
-	chmod +x php-cs-fixer.phar
-
-update-php-cs-fixer.phar:
-	rm -f php-cs-fixer.phar
-	make php-cs-fixer.phar
-
-lint-phpcsfixer: php8
-lint-phpcsfixer: php-cs-fixer.phar
-lint-phpcsfixer:
-	./php-cs-fixer.phar fix --dry-run --diff
+lint.phpcsfixer: export PHP_CS_FIXER_IGNORE_ENV = true
+lint.phpcsfixer: php8
+	vendor/bin/php-cs-fixer
 
-fix-phpcsfixer: php8
-fix-phpcsfixer: php-cs-fixer.phar
-fix-phpcsfixer:
-	./php-cs-fixer.phar fix
+fix.phpcsfixer: export PHP_CS_FIXER_IGNORE_ENV = true
+fix.phpcsfixer: php8
+	vendor/bin/php-cs-fixer fix
 
-lint-phpstan:
+lint.phpstan:
 	vendor/bin/phpstan analyse --memory-limit=-1
 
 ########
 # Test #
 ########
 
+## Run tests
 test:
 	vendor/bin/simple-phpunit
diff --git a/Model/FormTree.php b/Model/FormTree.php
index 76192f5..23ab5b6 100644
--- a/Model/FormTree.php
+++ b/Model/FormTree.php
@@ -14,11 +14,16 @@
  * A form Tree
  *
  * @author Thomas Jarrand <thomas.jarrand@gmail.com>
+ *
+ * @implements \Iterator<FormTreeNode>
+ * @implements \ArrayAccess<int,FormTreeNode>
  */
 class FormTree implements \Iterator, \Countable, \ArrayAccess
 {
     /**
      * The FormTreeNode elements
+     *
+     * @var array<FormTreeNode> $nodes
      */
     private array $nodes;
 
@@ -27,6 +32,9 @@ class FormTree implements \Iterator, \Countable, \ArrayAccess
      */
     private int $position = 0;
 
+    /**
+     * @param array<FormTreeNode> $nodes
+     */
     public function __construct(array $nodes = [])
     {
         $this->nodes = $nodes;
@@ -126,7 +134,7 @@ public function offsetExists($offset): bool
      * @param mixed $offset
      */
     #[\ReturnTypeWillChange]
-    public function offsetGet($offset): FormTreeNode
+    public function offsetGet($offset): ?FormTreeNode
     {
         return $this->offsetExists($offset) ? $this->nodes[$offset] : null;
     }
diff --git a/Tests/Builders/FormTreeBuilderTest.php b/Tests/Builders/FormTreeBuilderTest.php
index 486b13f..5c53466 100644
--- a/Tests/Builders/FormTreeBuilderTest.php
+++ b/Tests/Builders/FormTreeBuilderTest.php
@@ -33,13 +33,16 @@ public function testSimpleTreeBuilder(): void
         $barTree = $treeBuilder->getTree($formView['bar']);
 
         $this->assertEquals(1, \count($fooTree));
+        $this->assertNotNull($fooTree[0]);
         $this->assertEquals('foo', $fooTree[0]->getName());
         $this->assertEquals(true, $fooTree[0]->hasChildren());
 
         $this->assertEquals(2, \count($barTree));
+        $this->assertNotNull($barTree[0]);
         $this->assertEquals('foo', $barTree[0]->getName());
-        $this->assertEquals('bar', $barTree[1]->getName());
         $this->assertEquals(true, $barTree[0]->hasChildren());
+        $this->assertNotNull($barTree[1]);
+        $this->assertEquals('bar', $barTree[1]->getName());
         $this->assertEquals(false, $barTree[1]->hasChildren());
     }
 
@@ -64,11 +67,13 @@ public function testCollectionTreeBuilder(): void
         $formView = $form->createView();
         $tree = $treeBuilder->getTree($formView['bar']->vars['prototype']);
 
+        $this->assertNotNull($tree[1]);
         $this->assertEquals(true, $tree[1]->hasChildren());
         $this->assertEquals(true, $tree[1]->isCollection());
         $this->assertEquals(false, $tree[1]->isPrototype());
 
         $this->assertEquals(3, \count($tree));
+        $this->assertNotNull($tree[2]);
         $this->assertEquals(false, $tree[2]->hasChildren());
         $this->assertEquals(false, $tree[2]->isCollection());
         $this->assertEquals(true, $tree[2]->isPrototype());
diff --git a/Tests/FormTranslationTestCase.php b/Tests/FormTranslationTestCase.php
index 946802a..085de3e 100644
--- a/Tests/FormTranslationTestCase.php
+++ b/Tests/FormTranslationTestCase.php
@@ -13,13 +13,12 @@
 use Elao\Bundle\FormTranslationBundle\Form\Extension;
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\Form\Forms;
+use Symfony\Component\Form\FormFactoryInterface;
+use Symfony\Component\Form\FormTypeExtensionInterface;
 
 abstract class FormTranslationTestCase extends TestCase
 {
-    /**
-     * @var \Symfony\Component\Form\FormFactoryInterface
-     */
-    protected $factory;
+    protected FormFactoryInterface $factory;
 
     /**
      * {@inheritdoc}
@@ -34,17 +33,15 @@ protected function setUp(): void
     /**
      * Get Form Type Extensions
      *
-     * @return array
+     * @return array<FormTypeExtensionInterface>
      */
-    protected function getTypeExtensions()
+    protected function getTypeExtensions(): array
     {
-        $extensions = [
+        return [
             new Extension\ButtonTypeExtension(),
             new Extension\ChoiceTypeExtension(),
             new Extension\CollectionTypeExtension(),
             new Extension\FormTypeExtension(),
         ];
-
-        return $extensions;
     }
 }
diff --git a/composer.json b/composer.json
index 10e0929..e81694e 100644
--- a/composer.json
+++ b/composer.json
@@ -16,10 +16,10 @@
         }
     ],
     "require": {
-        "php": ">=7.4",
-        "symfony/framework-bundle": "~4.4|^5.1|^6.0",
-        "symfony/form": "~2.8|~3.0|~4.4|^5.1|^6.0",
-        "symfony/property-access": "~4.4|^5.1|^6.0"
+        "php": "^7.4|^8.0",
+        "symfony/framework-bundle": "^5.4|^6.0|^7.0",
+        "symfony/form": "^5.4|^6.0|^7.0",
+        "symfony/property-access": "^5.4|^6.0|^7.0"
     },
     "require-dev": {
         "ekino/phpstan-banned-code": "^1.0",
@@ -41,5 +41,10 @@
         "branch-alias": {
             "dev-master": "4.x-dev"
         }
+    },
+    "config": {
+        "allow-plugins": {
+            "phpstan/extension-installer": true
+        }
     }
 }
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index ee007f0..4af2a3b 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -1,5 +1,5 @@
 parameters:
-    level: 5
+    level: 8
 
     paths:
         - "./"