diff --git a/README.md b/README.md
index 404edf6..1a032a0 100644
--- a/README.md
+++ b/README.md
@@ -46,9 +46,12 @@ could use the library.
 
 require_once __DIR__ . '/vendor/autoload.php';
 
-use function Cspray\Labrador\engine;
+use Cspray\Labrador\Engine;
+use function Cspray\Labrador\bootstrap;
 
-$engine = engine();
+$injector = bootstrap();
+
+$engine = $injector->make(Engine::class);
 
 $engine->onAppExecute(function() {
     echo 'Hello World';
@@ -65,7 +68,7 @@ $engine->run();
 require_once './vendor/autoload.php';
 
 use Cspray\Labrador\CoreEngine;
-use Evenement\EventEmitterInterface;
+use League\Event\EmitterInterface;
 use function Cspray\Labrador\engine;
 
 class HelloWorldPlugin implements Plugin\EventAwarePlugin {
@@ -78,8 +81,8 @@ class HelloWorldPlugin implements Plugin\EventAwarePlugin {
         // our app is too simple to do anything here but yours might not be
     }
 
-    public function registerEventListeners(EventEmitterInterface $emitter) {
-        $emitter->on(CoreEngine::APP_EXECUTE_EVENT, function() {
+    public function registerEventListeners(EmitterInterface $emitter) {
+        $emitter->addListener(CoreEngine::APP_EXECUTE_EVENT, function() {
             echo 'Hello world!';
         });
     }
diff --git a/app.php b/app.php
index 9d24fbe..7e1ad20 100644
--- a/app.php
+++ b/app.php
@@ -2,12 +2,12 @@
 
 require_once __DIR__ . '/vendor/autoload.php';
 
-use Cspray\Labrador\CoreEngine;
+use Cspray\Labrador\Engine;
 use function Cspray\Labrador\bootstrap;
 
 $injector = bootstrap();
 
-$engine = $injector->make(CoreEngine::class);
+$engine = $injector->make(Engine::class);
 
 $engine->onAppExecute(function() {
     echo 'Hello World';
diff --git a/src/Cspray/Labrador/CoreEngine.php b/src/Cspray/Labrador/CoreEngine.php
index d89c838..02a2113 100644
--- a/src/Cspray/Labrador/CoreEngine.php
+++ b/src/Cspray/Labrador/CoreEngine.php
@@ -56,8 +56,8 @@ public function getEnvironment() : Environment {
         return $this->environment;
     }
 
-    public function onEnvironmentInitialize(callable $cb) : self {
-        $this->emitter->addListener(self::ENVIRONMENT_INITIALIZE_EVENT, $cb);
+    public function onEnvironmentInitialize(callable $cb, int $priority = EmitterInterface::P_NORMAL) : self {
+        $this->emitter->addListener(self::ENVIRONMENT_INITIALIZE_EVENT, $cb, $priority);
         return $this;
     }
 
@@ -65,8 +65,8 @@ public function onEnvironmentInitialize(callable $cb) : self {
      * @param callable $cb
      * @return $this
      */
-    public function onAppExecute(callable $cb) : self {
-        $this->emitter->addListener(self::APP_EXECUTE_EVENT, $cb);
+    public function onAppExecute(callable $cb, int $priority = EmitterInterface::P_NORMAL) : self {
+        $this->emitter->addListener(self::APP_EXECUTE_EVENT, $cb, $priority);
         return $this;
     }
 
@@ -74,8 +74,8 @@ public function onAppExecute(callable $cb) : self {
      * @param callable $cb
      * @return $this
      */
-    public function onAppCleanup(callable $cb) : self {
-        $this->emitter->addListener(self::APP_CLEANUP_EVENT, $cb);
+    public function onAppCleanup(callable $cb, int $priority = EmitterInterface::P_NORMAL) : self {
+        $this->emitter->addListener(self::APP_CLEANUP_EVENT, $cb, $priority);
         return $this;
     }
 
@@ -83,8 +83,8 @@ public function onAppCleanup(callable $cb) : self {
      * @param callable $cb
      * @return $this
      */
-    public function onExceptionThrown(callable $cb) : self {
-        $this->emitter->addListener(self::EXCEPTION_THROWN_EVENT, $cb);
+    public function onExceptionThrown(callable $cb, int $priority = EmitterInterface::P_NORMAL) : self {
+        $this->emitter->addListener(self::EXCEPTION_THROWN_EVENT, $cb, $priority);
         return $this;
     }
 
diff --git a/src/Cspray/Labrador/PluginManager.php b/src/Cspray/Labrador/PluginManager.php
index c7897e1..8fe8fc0 100644
--- a/src/Cspray/Labrador/PluginManager.php
+++ b/src/Cspray/Labrador/PluginManager.php
@@ -41,7 +41,7 @@ private function registerBooter() {
         };
         $cb = $cb->bindTo($this);
 
-        $this->emitter->addListener(Engine::ENVIRONMENT_INITIALIZE_EVENT, $cb);
+        $this->emitter->addListener(Engine::ENVIRONMENT_INITIALIZE_EVENT, $cb, EmitterInterface::P_HIGH);
     }
 
     public function registerPlugin(Plugin $plugin) {
diff --git a/src/Cspray/Labrador/Services.php b/src/Cspray/Labrador/Services.php
index f8d0e57..0e957de 100644
--- a/src/Cspray/Labrador/Services.php
+++ b/src/Cspray/Labrador/Services.php
@@ -49,7 +49,7 @@ public function createInjector() : Injector {
             $emitter = $injector->make(EmitterInterface::class);
             $emitter->addListener(Engine::ENVIRONMENT_INITIALIZE_EVENT, function(EnvironmentInitializeEvent $event) {
                 $event->getEnvironment()->runInitializers();
-            });
+            }, EmitterInterface::P_HIGH);
         }
 
         return $injector;