diff --git a/composer.json b/composer.json
index 9db659b..a1d12d7 100644
--- a/composer.json
+++ b/composer.json
@@ -29,13 +29,13 @@
     "require": {
         "php": ">=5.3",
         "evenement/evenement": "^3.0 || ^2.0 || ^1.0",
-        "react/dns": "^1.7",
+        "react/dns": "^1.13",
         "react/event-loop": "^1.2",
-        "react/promise": "^3 || ^2.1 || ^1.2"
+        "react/promise": "^3.2 || ^2.1 || ^1.2"
     },
     "require-dev": {
         "phpunit/phpunit": "^9.6 || ^5.7 || ^4.8.36",
-        "react/async": "^4 || ^3 || ^2"
+        "react/async": "^4.3 || ^3 || ^2"
     },
     "autoload": {
         "psr-4": {
diff --git a/src/Factory.php b/src/Factory.php
index 89586a6..d7836d7 100644
--- a/src/Factory.php
+++ b/src/Factory.php
@@ -29,8 +29,15 @@ class Factory
      *     try to load the system default DNS config or fall back to using
      *     Google's public DNS 8.8.8.8
      */
-    public function __construct(LoopInterface $loop = null, ResolverInterface $resolver = null)
+    public function __construct($loop = null, $resolver = null)
     {
+        if ($loop !== null && !$loop instanceof LoopInterface) { // manual type check to support legacy PHP < 7.1
+            throw new \InvalidArgumentException('Argument #1 ($loop) expected null|React\EventLoop\LoopInterface');
+        }
+        if ($resolver !== null && !$resolver instanceof ResolverInterface) { // manual type check to support legacy PHP < 7.1
+            throw new \InvalidArgumentException('Argument #2 ($resolver) expected null|React\Dns\Resolver\ResolverInterface');
+        }
+
         $loop = $loop ?: Loop::get();
         if ($resolver === null) {
             // try to load nameservers from system config or default to Google's public DNS
diff --git a/src/Socket.php b/src/Socket.php
index e06723c..465154c 100644
--- a/src/Socket.php
+++ b/src/Socket.php
@@ -15,8 +15,17 @@ class Socket extends EventEmitter implements SocketInterface
 
     public $bufferSize = 65536;
 
-    public function __construct(LoopInterface $loop, $socket, Buffer $buffer = null)
+    /**
+     * @param LoopInterface $loop
+     * @param resource $socket
+     * @param ?Buffer $buffer
+     */
+    public function __construct(LoopInterface $loop, $socket, $buffer = null)
     {
+        if ($buffer !== null && !$buffer instanceof Buffer) { // manual type check to support legacy PHP < 7.1
+            throw new \InvalidArgumentException('Argument #3 ($buffer) expected null|React\Datagram\Buffer');
+        }
+
         $this->loop = $loop;
         $this->socket = $socket;
 
diff --git a/tests/FactoryTest.php b/tests/FactoryTest.php
index 228ab6d..e8df249 100644
--- a/tests/FactoryTest.php
+++ b/tests/FactoryTest.php
@@ -33,6 +33,18 @@ public function testConstructWithoutLoopAssignsLoopAutomatically()
         $this->assertInstanceOf('React\EventLoop\LoopInterface', $loop);
     }
 
+    public function testCtorThrowsForInvalidLoop()
+    {
+        $this->setExpectedException('InvalidArgumentException', 'Argument #1 ($loop) expected null|React\EventLoop\LoopInterface');
+        new Factory('loop');
+    }
+
+    public function testCtorThrowsForInvalidResolver()
+    {
+        $this->setExpectedException('InvalidArgumentException', 'Argument #2 ($resolver) expected null|React\Dns\Resolver\ResolverInterface');
+        new Factory(null, 'resolver');
+    }
+
     public function testCreateClient()
     {
         $this->resolver->expects($this->never())->method('resolve');
diff --git a/tests/SocketTest.php b/tests/SocketTest.php
index bdc82f5..f728670 100644
--- a/tests/SocketTest.php
+++ b/tests/SocketTest.php
@@ -18,6 +18,15 @@ public function setUpFactory()
         $this->factory = new \React\Datagram\Factory($this->loop, $this->createResolverMock());
     }
 
+    public function testCtorThrowsForInvalidBuffer()
+    {
+        $socket = stream_socket_server('udp://127.0.0.1:0', $errno, $errstr, STREAM_SERVER_BIND);
+        assert(is_resource($socket));
+
+        $this->setExpectedException('InvalidArgumentException', 'Argument #3 ($buffer) expected null|React\Datagram\Buffer');
+        new Socket($this->loop, $socket, 'buffer');
+    }
+
     /**
      * @doesNotPerformAssertions
      */