diff --git a/.dockerignore b/.dockerignore
index a878b84..176e243 100644
--- a/.dockerignore
+++ b/.dockerignore
@@ -1,4 +1,4 @@
-tests/Extension/Symfony/fixtures/app/var/
+tests/Extension/Symfony/Fixtures/app/var/
 vendor/
 .phpunit.result.cache
 composer.lock
diff --git a/.gitignore b/.gitignore
index a878b84..176e243 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,4 @@
-tests/Extension/Symfony/fixtures/app/var/
+tests/Extension/Symfony/Fixtures/app/var/
 vendor/
 .phpunit.result.cache
 composer.lock
diff --git a/Dockerfile b/Dockerfile
index 1418bb9..66b7df1 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -7,7 +7,7 @@ ARG DEPENDENCIES=highest
 RUN set -eux; \
     apk add --no-cache acl libzip; \
     apk add --no-cache --virtual .build-deps ${PHPIZE_DEPS} zlib-dev libzip-dev; \
-    docker-php-ext-install zip; \
+    docker-php-ext-install zip opcache; \
     pecl install pcov;\
     docker-php-ext-enable pcov; \
     apk del .build-deps;
diff --git a/Makefile b/Makefile
index d3e54f7..a4f3b24 100644
--- a/Makefile
+++ b/Makefile
@@ -27,4 +27,4 @@ test_all_targets:
 
 psalm:
 	docker build -t yohang/finite:php-8.4 --build-arg PHP_VERSION=8.4 .
-	docker run -it --rm yohang/finite:php-8.4 php ./vendor/bin/psalm --show-info=true
+	docker run -it --rm yohang/finite:php-8.4 php ./vendor/bin/psalm --show-info=true --no-diff
diff --git a/composer.json b/composer.json
index f63af81..8b93c8e 100644
--- a/composer.json
+++ b/composer.json
@@ -21,7 +21,8 @@
     ],
     "require": {
         "php": ">=8.1",
-        "symfony/property-access": ">=5.4,<8"
+        "symfony/property-access": ">=5.4,<8",
+        "psr/event-dispatcher": "^1.0"
     },
     "require-dev": {
         "phpunit/phpunit": "^10.5.40",
@@ -29,7 +30,9 @@
         "twig/twig": "^3.4",
         "vimeo/psalm": "dev-master@dev",
         "symfony/http-kernel": ">=5.4,<8",
-        "symfony/framework-bundle": ">=5.4,<8"
+        "symfony/framework-bundle": ">=5.4,<8",
+        "symfony/event-dispatcher": ">=5.4,<8",
+        "symfony/stopwatch": ">=5.4,<8"
     },
     "autoload": {
         "psr-4": {
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 5986202..f94b046 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -2,7 +2,7 @@
 <!-- http://www.phpunit.de/manual/current/en/appendixes.configuration.html -->
 <phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          colors="true"
-         bootstrap="tests/Extension/Symfony/fixtures/app/bootstrap.php"
+         bootstrap="tests/Extension/Symfony/Fixtures/app/bootstrap.php"
          xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.5/phpunit.xsd">
     <source>
         <include>
diff --git a/psalm.xml b/psalm.xml
index 4d5b24a..9b8659d 100644
--- a/psalm.xml
+++ b/psalm.xml
@@ -1,6 +1,6 @@
 <?xml version="1.0"?>
 <psalm
-    errorLevel="7"
+    errorLevel="1"
     resolveFromConfigFile="true"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xmlns="https://getpsalm.org/schema/config"
diff --git a/src/Event/Event.php b/src/Event/Event.php
index 2f795d3..fb6f3ea 100644
--- a/src/Event/Event.php
+++ b/src/Event/Event.php
@@ -2,7 +2,9 @@
 
 namespace Finite\Event;
 
-abstract class Event
+use Psr\EventDispatcher\StoppableEventInterface;
+
+abstract class Event implements StoppableEventInterface
 {
     private bool $propagationStopped = false;
 
diff --git a/src/Event/EventDispatcher.php b/src/Event/EventDispatcher.php
index df7535e..a375ce6 100644
--- a/src/Event/EventDispatcher.php
+++ b/src/Event/EventDispatcher.php
@@ -2,7 +2,10 @@
 
 namespace Finite\Event;
 
-class EventDispatcher
+use Psr\EventDispatcher\EventDispatcherInterface;
+use Psr\EventDispatcher\StoppableEventInterface;
+
+class EventDispatcher implements EventDispatcherInterface
 {
     /**
      * @var array<string,array<callable>>
@@ -18,7 +21,7 @@ public function addEventListener(string $eventClass, callable $listener): void
         $this->listeners[$eventClass][] = $listener;
     }
 
-    public function dispatch(Event $event): void
+    public function dispatch(object $event): void
     {
         if (!isset($this->listeners[get_class($event)])) {
             return;
@@ -27,7 +30,7 @@ public function dispatch(Event $event): void
         foreach ($this->listeners[get_class($event)] as $listener) {
             $listener($event);
 
-            if ($event->isPropagationStopped()) {
+            if ($event instanceof StoppableEventInterface && $event->isPropagationStopped()) {
                 return;
             }
         }
diff --git a/src/Extension/Symfony/Bundle/DependencyInjection/FiniteExtension.php b/src/Extension/Symfony/Bundle/DependencyInjection/FiniteExtension.php
index 39c5caf..cf2a123 100644
--- a/src/Extension/Symfony/Bundle/DependencyInjection/FiniteExtension.php
+++ b/src/Extension/Symfony/Bundle/DependencyInjection/FiniteExtension.php
@@ -8,6 +8,7 @@
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Definition;
 use Symfony\Component\DependencyInjection\Extension\Extension;
+use Symfony\Component\DependencyInjection\Reference;
 
 final class FiniteExtension extends Extension
 {
@@ -15,7 +16,9 @@ public function load(array $configs, ContainerBuilder $container): void
     {
         $container->addDefinitions(
             [
-                StateMachine::class => (new Definition(StateMachine::class))->setPublic(true),
+                StateMachine::class => (new Definition(StateMachine::class))
+                    ->setArgument('$dispatcher', new Reference('event_dispatcher'))
+                    ->setPublic(true),
                 TwigExtension::class => new Definition(TwigExtension::class),
             ]
         );
diff --git a/src/StateMachine.php b/src/StateMachine.php
index 7603f85..4e7bb0b 100644
--- a/src/StateMachine.php
+++ b/src/StateMachine.php
@@ -7,15 +7,15 @@
 use Finite\Event\PostTransitionEvent;
 use Finite\Event\PreTransitionEvent;
 use Finite\Transition\TransitionInterface;
+use Psr\EventDispatcher\EventDispatcherInterface;
 use Symfony\Component\PropertyAccess\PropertyAccess;
 
 class StateMachine
 {
     public function __construct(
-        private readonly EventDispatcher $dispatcher = new EventDispatcher,
+        private readonly EventDispatcherInterface $dispatcher = new EventDispatcher,
     )
     {
-
     }
 
     /**
@@ -85,6 +85,11 @@ public function getReachablesTransitions(object $object, ?string $stateClass = n
         );
     }
 
+    public function getDispatcher(): EventDispatcherInterface
+    {
+        return $this->dispatcher;
+    }
+
     /**
      * @param class-string|null $stateClass
      */
@@ -92,6 +97,7 @@ private function extractState(object $object, ?string $stateClass = null): State
     {
         $property = $this->extractStateProperty($object, $stateClass);
 
+        /** @psalm-suppress MixedReturnStatement */
         return PropertyAccess::createPropertyAccessor()->getValue($object, $property->getName());
     }
 
@@ -107,11 +113,8 @@ private function extractStateProperty(object $object, ?string $stateClass = null
         $reflectionClass = new \ReflectionClass($object);
         /** @psalm-suppress DocblockTypeContradiction */
         do {
-            if (!$reflectionClass) {
-                throw new \InvalidArgumentException('Found no state on object ' . get_class($object));
-            }
-
             foreach ($reflectionClass->getProperties() as $property) {
+                /** @var \ReflectionUnionType|\ReflectionIntersectionType|\ReflectionNamedType $reflectionType */
                 $reflectionType = $property->getType();
                 if (null === $reflectionType) {
                     continue;
@@ -125,10 +128,6 @@ private function extractStateProperty(object $object, ?string $stateClass = null
                     continue;
                 }
 
-                if (!$reflectionType instanceof \ReflectionNamedType) {
-                    continue;
-                }
-
                 /** @var class-string $name */
                 $name = $reflectionType->getName();
                 if (!enum_exists($name)) {
diff --git a/src/Transition/Transition.php b/src/Transition/Transition.php
index f230ae6..31f86ae 100644
--- a/src/Transition/Transition.php
+++ b/src/Transition/Transition.php
@@ -14,8 +14,10 @@ class Transition implements TransitionInterface
 {
     public function __construct(
         public readonly string $name,
+        /** @var State[] */
         public readonly array $sourceStates,
         public readonly State $targetState,
+        /** @var array<string, string> */
         public readonly array $properties = []
     )
     {
diff --git a/tests/E2E/BasicGraphTest.php b/tests/E2E/BasicGraphTest.php
index bbb97f8..5c3e904 100644
--- a/tests/E2E/BasicGraphTest.php
+++ b/tests/E2E/BasicGraphTest.php
@@ -7,6 +7,14 @@
 
 class Article
 {
+    public  $noTypeHere = null;
+
+    public  int|float $unionType = 0;
+
+    public  \Traversable&\Countable $intersectionType;
+
+    public string $namedType = 'named';
+
     private SimpleArticleState $state = SimpleArticleState::DRAFT;
 
     private readonly \DateTimeInterface $createdAt;
diff --git a/tests/Extension/Symfony/Bundle/DependencyInjection/FiniteExtensionTest.php b/tests/Extension/Symfony/Bundle/DependencyInjection/FiniteExtensionTest.php
new file mode 100644
index 0000000..143833e
--- /dev/null
+++ b/tests/Extension/Symfony/Bundle/DependencyInjection/FiniteExtensionTest.php
@@ -0,0 +1,31 @@
+<?php
+declare(strict_types=1);
+
+namespace Finite\Tests\Extension\Symfony\Bundle\DependencyInjection;
+
+use Finite\Extension\Symfony\Bundle\DependencyInjection\FiniteExtension;
+use Finite\Extension\Twig\FiniteExtension as TwigExtension;
+use Finite\StateMachine;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+
+class FiniteExtensionTest extends TestCase
+{
+    public function test_it_loads_services(): void
+    {
+        $container = $this->getMockBuilder(ContainerBuilder::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+
+        $container->expects($this->once())->method('addDefinitions')->with(
+            $this->logicalAnd(
+                $this->countOf(2),
+                $this->arrayHasKey(StateMachine::class),
+                $this->arrayHasKey(TwigExtension::class),
+            ),
+        );
+
+        $extension = new FiniteExtension;
+        $extension->load([], $container);
+    }
+}
diff --git a/tests/Extension/Symfony/Fixtures/Model/Document.php b/tests/Extension/Symfony/Fixtures/Model/Document.php
new file mode 100644
index 0000000..58a927f
--- /dev/null
+++ b/tests/Extension/Symfony/Fixtures/Model/Document.php
@@ -0,0 +1,11 @@
+<?php
+declare(strict_types=1);
+
+namespace Finite\Tests\Extension\Symfony\Fixtures\Model;
+
+use Finite\Tests\Extension\Symfony\Fixtures\State\DocumentState;
+
+class Document
+{
+    public DocumentState $state = DocumentState::DRAFT;
+}
diff --git a/tests/Extension/Symfony/Fixtures/State/DocumentState.php b/tests/Extension/Symfony/Fixtures/State/DocumentState.php
new file mode 100644
index 0000000..ebd0880
--- /dev/null
+++ b/tests/Extension/Symfony/Fixtures/State/DocumentState.php
@@ -0,0 +1,25 @@
+<?php
+declare(strict_types=1);
+
+namespace Finite\Tests\Extension\Symfony\Fixtures\State;
+
+use Finite\State;
+use Finite\Transition\Transition;
+
+enum DocumentState: string implements State
+{
+    case DRAFT = 'draft';
+    case PUBLISHED = 'published';
+    case REPORTED = 'reported';
+    case DISABLED = 'disabled';
+
+    public static function getTransitions(): array
+    {
+        return [
+            new Transition('publish', [self::DRAFT], self::PUBLISHED),
+            new Transition('clear', [self::REPORTED, self::DISABLED], self::PUBLISHED),
+            new Transition('report', [self::PUBLISHED], self::REPORTED),
+            new Transition('disable', [self::REPORTED, self::PUBLISHED], self::DISABLED),
+        ];
+    }
+}
diff --git a/tests/Extension/Symfony/fixtures/app/AppKernel.php b/tests/Extension/Symfony/Fixtures/app/AppKernel.php
similarity index 84%
rename from tests/Extension/Symfony/fixtures/app/AppKernel.php
rename to tests/Extension/Symfony/Fixtures/app/AppKernel.php
index 428781e..bff97d2 100644
--- a/tests/Extension/Symfony/fixtures/app/AppKernel.php
+++ b/tests/Extension/Symfony/Fixtures/app/AppKernel.php
@@ -20,7 +20,8 @@ public function registerBundles(): iterable
 
     protected function configureContainer(ContainerBuilder $c, LoaderInterface $loader): void
     {
-        $c->prependExtensionConfig('framework', ['test' => true]);
+        $c->setParameter('kernel.debug', true);
+        $c->prependExtensionConfig('framework', ['test' => true, 'profiler' => true]);
     }
 
     public function getProjectDir(): string
diff --git a/tests/Extension/Symfony/fixtures/app/bootstrap.php b/tests/Extension/Symfony/Fixtures/app/bootstrap.php
similarity index 100%
rename from tests/Extension/Symfony/fixtures/app/bootstrap.php
rename to tests/Extension/Symfony/Fixtures/app/bootstrap.php
diff --git a/tests/Extension/Symfony/ServiceTest.php b/tests/Extension/Symfony/ServiceTest.php
index 1a4e4d5..62fec84 100644
--- a/tests/Extension/Symfony/ServiceTest.php
+++ b/tests/Extension/Symfony/ServiceTest.php
@@ -3,19 +3,35 @@
 
 namespace Finite\Tests\Extension\Symfony;
 
-use Finite\Extension\Twig\FiniteExtension;
+use Finite\Event\CanTransitionEvent;
 use Finite\StateMachine;
+use Finite\Tests\Extension\Symfony\Fixtures\Model\Document;
 use Symfony\Bundle\FrameworkBundle\Test\KernelTestCase;
-use Symfony\Bundle\FrameworkBundle\Test\TestContainer;
+use Symfony\Component\EventDispatcher\Debug\TraceableEventDispatcher;
+use Symfony\Contracts\EventDispatcher\EventDispatcherInterface;
 
 class ServiceTest extends KernelTestCase
 {
     public function test_services_are_registered(): void
     {
-        /** @var TestContainer $container */
         $container = static::getContainer();
 
         $this->assertInstanceOf(StateMachine::class, $container->get(StateMachine::class));
+        $this->assertInstanceOf(EventDispatcherInterface::class, $container->get(StateMachine::class)->getDispatcher());
+    }
+
+    public function test_it_uses_the_symfony_dispatcher(): void
+    {
+        $container = static::getContainer();
+
+        /** @var StateMachine $stateMachine */
+        $stateMachine = $container->get(StateMachine::class);
+        $stateMachine->can(new Document, 'publish');
+
+        /** @var TraceableEventDispatcher $debugDispatcher */
+        $debugDispatcher = $container->get('debug.event_dispatcher');
+
+        $this->assertSame(CanTransitionEvent::class, $debugDispatcher->getOrphanedEvents()[0]);
     }
 
     protected static function getKernelClass(): string
diff --git a/tests/Extension/Twig/FiniteExtensionTest.php b/tests/Extension/Twig/FiniteExtensionTest.php
new file mode 100644
index 0000000..d0d8923
--- /dev/null
+++ b/tests/Extension/Twig/FiniteExtensionTest.php
@@ -0,0 +1,32 @@
+<?php
+declare(strict_types=1);
+
+namespace Finite\Tests\Extension\Twig;
+
+use Finite\Extension\Twig\FiniteExtension;
+use Finite\StateMachine;
+use PHPUnit\Framework\TestCase;
+
+class FiniteExtensionTest extends TestCase
+{
+    public function test_it_declare_twig_functions(): void
+    {
+        $object = $this->createMock(\stdClass::class);
+        $stateMachine = $this->createMock(StateMachine::class);
+
+        $functions = (new FiniteExtension($stateMachine))->getFunctions();
+
+        $functions = array_combine(
+            array_map(fn($function) => $function->getName(), $functions),
+            $functions,
+        );
+        $this->assertArrayHasKey('finite_can', $functions);
+        $this->assertArrayHasKey('finite_reachable_transitions', $functions);
+
+        $stateMachine->expects($this->once())->method('can')->with($object, 'publish')->willReturn(true);
+        $functions['finite_can']->getCallable()($object, 'publish');
+
+        $stateMachine->expects($this->once())->method('getReachablesTransitions')->with($object)->willReturn([]);
+        $functions['finite_reachable_transitions']->getCallable()($object);
+    }
+}
diff --git a/tests/StateMachineTest.php b/tests/StateMachineTest.php
index 1cd0dd5..abde7a7 100644
--- a/tests/StateMachineTest.php
+++ b/tests/StateMachineTest.php
@@ -9,14 +9,28 @@
 use Finite\Tests\E2E\Article;
 use Finite\Tests\E2E\SimpleArticleState;
 use PHPUnit\Framework\TestCase;
+use Psr\EventDispatcher\EventDispatcherInterface;
 
 class StateMachineTest extends TestCase
 {
+    public function test_it_instantiate_event_dispatcher(): void
+    {
+        $this->assertInstanceOf(EventDispatcher::class, (new StateMachine)->getDispatcher());
+        $this->assertInstanceOf(EventDispatcherInterface::class, (new StateMachine)->getDispatcher());
+    }
+
+    public function test_it_use_constructor_event_dispatcher(): void
+    {
+        $eventDispatcher = $this->getMockBuilder(EventDispatcherInterface::class)->getMock();
+
+        $this->assertSame($eventDispatcher, (new StateMachine($eventDispatcher))->getDispatcher());
+    }
+
     public function test_it_can_transition(): void
     {
         $object = new Article('Hi !');
 
-        $eventDispatcher = $this->getMockBuilder(EventDispatcher::class)->getMock();
+        $eventDispatcher = $this->getMockBuilder(EventDispatcherInterface::class)->getMock();
         $eventDispatcher
             ->expects($this->once())
             ->method('dispatch')
@@ -29,7 +43,6 @@ public function test_it_can_transition(): void
                 }),
             );
 
-
         $stateMachine = new StateMachine($eventDispatcher);
 
         $this->assertTrue($stateMachine->can($object, SimpleArticleState::PUBLISH));
@@ -39,7 +52,7 @@ public function test_it_blocks_transition(): void
     {
         $object = new Article('Hi !');
 
-        $eventDispatcher = $this->getMockBuilder(EventDispatcher::class)->getMock();
+        $eventDispatcher = $this->getMockBuilder(EventDispatcherInterface::class)->getMock();
         $eventDispatcher
             ->expects($this->once())
             ->method('dispatch')
@@ -56,7 +69,7 @@ public function test_it_applies_transition(): void
     {
         $object = new Article('Hi !');
 
-        $eventDispatcher = $this->getMockBuilder(EventDispatcher::class)->getMock();
+        $eventDispatcher = $this->getMockBuilder(EventDispatcherInterface::class)->getMock();
 
         $matcher = $this->exactly(6);
         $eventDispatcher
@@ -93,4 +106,12 @@ public function test_it_rejects_unexistant_state_class()
 
         (new StateMachine)->can(new \stdClass, 'transition', 'Unexistant enum');
     }
+
+    public function test_it_throws_if_no_state(): void
+    {
+        $this->expectException(\InvalidArgumentException::class);
+
+        $stateMachine = new StateMachine;
+        $stateMachine->can(new class extends \stdClass {}, 'transition');
+    }
 }