diff --git a/src/Ratchet/App.php b/src/Ratchet/App.php
index d3de200..e7e023c 100644
--- a/src/Ratchet/App.php
+++ b/src/Ratchet/App.php
@@ -63,7 +63,12 @@ class App {
      * @param LoopInterface $loop       Specific React\EventLoop to bind the application to. null will create one for you.
      * @param array         $context
      */
-    public function __construct($httpHost = 'localhost', $port = 8080, $address = '127.0.0.1', LoopInterface $loop = null, $context = array()) {
+    public function __construct(?string $httpHost = null, ?int $port = null, ?string $address = null, ?LoopInterface $loop = null, ?array $context = null) {
+        if ($httpHost == null) $httpHost = 'localhost';
+        if ($port == null) $port = 80;
+        if ($address == null) $address = '127.0.0.1';
+        if ($context == null) $context = array();
+
         if (extension_loaded('xdebug') && getenv('RATCHET_DISABLE_XDEBUG_WARN') === false) {
             trigger_error('XDebug extension detected. Remember to disable this if performance testing or going live!', E_USER_WARNING);
         }
diff --git a/src/Ratchet/Http/HttpServerInterface.php b/src/Ratchet/Http/HttpServerInterface.php
index 2c37c49..5990d03 100644
--- a/src/Ratchet/Http/HttpServerInterface.php
+++ b/src/Ratchet/Http/HttpServerInterface.php
@@ -10,5 +10,5 @@ interface HttpServerInterface extends MessageComponentInterface {
      * @param \Psr\Http\Message\RequestInterface    $request null is default because PHP won't let me overload; don't pass null!!!
      * @throws \UnexpectedValueException if a RequestInterface is not passed
      */
-    public function onOpen(ConnectionInterface $conn, RequestInterface $request = null);
+    public function onOpen(ConnectionInterface $conn, ?RequestInterface $request = null);
 }
diff --git a/src/Ratchet/Http/NoOpHttpServerController.php b/src/Ratchet/Http/NoOpHttpServerController.php
index 4f72e66..fcaca02 100644
--- a/src/Ratchet/Http/NoOpHttpServerController.php
+++ b/src/Ratchet/Http/NoOpHttpServerController.php
@@ -4,7 +4,7 @@ use Ratchet\ConnectionInterface;
 use Psr\Http\Message\RequestInterface;
 
 class NoOpHttpServerController implements HttpServerInterface {
-    public function onOpen(ConnectionInterface $conn, RequestInterface $request = null) {
+    public function onOpen(ConnectionInterface $conn, ?RequestInterface $request = null) {
     }
 
     public function onMessage(ConnectionInterface $from, $msg) {
diff --git a/src/Ratchet/Http/OriginCheck.php b/src/Ratchet/Http/OriginCheck.php
index 2bdc0f7..29b2dad 100644
--- a/src/Ratchet/Http/OriginCheck.php
+++ b/src/Ratchet/Http/OriginCheck.php
@@ -31,7 +31,7 @@ class OriginCheck implements HttpServerInterface {
     /**
      * {@inheritdoc}
      */
-    public function onOpen(ConnectionInterface $conn, RequestInterface $request = null) {
+    public function onOpen(ConnectionInterface $conn, ?RequestInterface $request = null) {
         $header = (string)$request->getHeader('Origin')[0];
         $origin = parse_url($header, PHP_URL_HOST) ?: $header;
 
diff --git a/src/Ratchet/Http/Router.php b/src/Ratchet/Http/Router.php
index 2bd5942..04ea395 100644
--- a/src/Ratchet/Http/Router.php
+++ b/src/Ratchet/Http/Router.php
@@ -26,7 +26,7 @@ class Router implements HttpServerInterface {
      * {@inheritdoc}
      * @throws \UnexpectedValueException If a controller is not \Ratchet\Http\HttpServerInterface
      */
-    public function onOpen(ConnectionInterface $conn, RequestInterface $request = null) {
+    public function onOpen(ConnectionInterface $conn, ?RequestInterface $request = null) {
         if (null === $request) {
             throw new \UnexpectedValueException('$request can not be null');
         }
diff --git a/src/Ratchet/Session/SessionProvider.php b/src/Ratchet/Session/SessionProvider.php
index 44276c5..2f42a17 100644
--- a/src/Ratchet/Session/SessionProvider.php
+++ b/src/Ratchet/Session/SessionProvider.php
@@ -44,7 +44,9 @@ class SessionProvider implements HttpServerInterface {
      * @param \Ratchet\Session\Serialize\HandlerInterface $serializer
      * @throws \RuntimeException
      */
-    public function __construct(HttpServerInterface $app, \SessionHandlerInterface $handler, array $options = array(), HandlerInterface $serializer = null) {
+    public function __construct(HttpServerInterface $app, \SessionHandlerInterface $handler, ?array $options = null, ?HandlerInterface $serializer = null) {
+        if ($options == null) $options = array();
+
         $this->_app     = $app;
         $this->_handler = $handler;
         $this->_null    = new NullSessionHandler;
@@ -70,7 +72,7 @@ class SessionProvider implements HttpServerInterface {
     /**
      * {@inheritdoc}
      */
-    public function onOpen(ConnectionInterface $conn, RequestInterface $request = null) {
+    public function onOpen(ConnectionInterface $conn, ?RequestInterface $request = null) {
         $sessionName = ini_get('session.name');
 
         $id = array_reduce($request->getHeader('Cookie'), function($accumulator, $cookie) use ($sessionName) {
diff --git a/src/Ratchet/WebSocket/WsServer.php b/src/Ratchet/WebSocket/WsServer.php
index 27795ca..2b1767c 100644
--- a/src/Ratchet/WebSocket/WsServer.php
+++ b/src/Ratchet/WebSocket/WsServer.php
@@ -104,7 +104,7 @@ class WsServer implements HttpServerInterface {
     /**
      * {@inheritdoc}
      */
-    public function onOpen(ConnectionInterface $conn, RequestInterface $request = null) {
+    public function onOpen(ConnectionInterface $conn, ?RequestInterface $request = null) {
         if (null === $request) {
             throw new \UnexpectedValueException('$request can not be null');
         }