diff --git a/flight/Engine.php b/flight/Engine.php
index e2c1dc3..a26c1ff 100644
--- a/flight/Engine.php
+++ b/flight/Engine.php
@@ -490,6 +490,7 @@ class Engine
             $this->unregister('response');
             $this->register('request', Request::class);
             $this->register('response', Response::class);
+            $this->router()->reset();
         }
         $request = $this->request();
         $response = $this->response();
@@ -513,7 +514,6 @@ class Engine
 
         // Route the request
         $failedMiddlewareCheck = false;
-
         while ($route = $router->route($request)) {
             $params = array_values($route->params);
 
diff --git a/tests/FlightAsyncTest.php b/tests/FlightAsyncTest.php
new file mode 100644
index 0000000..1a53f44
--- /dev/null
+++ b/tests/FlightAsyncTest.php
@@ -0,0 +1,83 @@
+<?php
+
+declare(strict_types=1);
+
+namespace tests;
+
+use Flight;
+use flight\Engine;
+use PHPUnit\Framework\TestCase;
+
+class FlightAsyncTest extends TestCase
+{
+    public static function setUpBeforeClass(): void
+    {
+        Flight::setEngine(new Engine());
+    }
+
+    protected function setUp(): void
+    {
+        $_SERVER = [];
+        $_REQUEST = [];
+    }
+
+    protected function tearDown(): void
+    {
+        unset($_REQUEST);
+        unset($_SERVER);
+    }
+
+    // Checks that default components are loaded
+    public function testSingleRoute()
+    {
+        Flight::route('GET /', function () {
+            echo 'hello world';
+        });
+
+        $this->expectOutputString('hello world');
+        Flight::start();
+    }
+
+    public function testMultipleRoutes()
+    {
+        Flight::route('GET /', function () {
+            echo 'hello world';
+        });
+
+        Flight::route('GET /test', function () {
+            echo 'test';
+        });
+
+        $this->expectOutputString('test');
+        $_SERVER['REQUEST_URI'] = '/test';
+        Flight::start();
+    }
+
+    public function testMultipleStartsSingleRoute()
+    {
+        Flight::route('GET /', function () {
+            echo 'hello world';
+        });
+
+        $this->expectOutputString('hello worldhello world');
+        Flight::start();
+        Flight::start();
+    }
+
+    public function testMultipleStartsMultipleRoutes()
+    {
+        Flight::route('GET /', function () {
+            echo 'hello world';
+        });
+
+        Flight::route('GET /test', function () {
+            echo 'test';
+        });
+
+        $this->expectOutputString('testhello world');
+        $_SERVER['REQUEST_URI'] = '/test';
+        Flight::start();
+        $_SERVER['REQUEST_URI'] = '/';
+        Flight::start();
+    }
+}