diff --git a/.travis.yml b/.travis.yml
index b45fd6e..11d51b4 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -17,4 +17,4 @@ before_script:
     - sh tests/ab/run_ab_tests.sh
 
 script:
-    - phpunit
+    - vendor/bin/phpunit
diff --git a/composer.json b/composer.json
index 77d9fde..224066b 100644
--- a/composer.json
+++ b/composer.json
@@ -26,6 +26,7 @@
     },
     "require-dev": {
         "react/http": "^0.4.1",
-        "react/socket-client": "^0.4.3"
+        "react/socket-client": "^0.4.3",
+        "phpunit/phpunit": "4.8.*"
     }
 }
diff --git a/src/Handshake/ServerNegotiator.php b/src/Handshake/ServerNegotiator.php
index 6568684..5a0073b 100644
--- a/src/Handshake/ServerNegotiator.php
+++ b/src/Handshake/ServerNegotiator.php
@@ -55,20 +55,28 @@ class ServerNegotiator implements NegotiatorInterface {
             return new Response(400);
         }
 
+        $upgradeSuggestion = [
+            'Connection'             => 'Upgrade',
+            'Upgrade'                => 'websocket',
+            'Sec-WebSocket-Version'  => $this->getVersionNumber()
+        ];
+        if (count($this->_supportedSubProtocols) > 0) {
+            $upgradeSuggestion['Sec-WebSocket-Protocol'] = implode(', ', $this->_supportedSubProtocols);
+        }
         if (true !== $this->verifier->verifyUpgradeRequest($request->getHeader('Upgrade'))) {
-            return new Response(400, [], '1.1', null, 'Upgrade header MUST be provided');
+            return new Response(426, $upgradeSuggestion, null, '1.1', 'Upgrade header MUST be provided');
         }
 
         if (true !== $this->verifier->verifyConnection($request->getHeader('Connection'))) {
-            return new Response(400, [], '1.1', null, 'Connection header MUST be provided');
+            return new Response(400, [], null, '1.1', 'Connection Upgrade MUST be requested');
         }
 
         if (true !== $this->verifier->verifyKey($request->getHeader('Sec-WebSocket-Key'))) {
-            return new Response(400, [], '1.1', null, 'Invalid Sec-WebSocket-Key');
+            return new Response(400, [], null, '1.1', 'Invalid Sec-WebSocket-Key');
         }
 
         if (true !== $this->verifier->verifyVersion($request->getHeader('Sec-WebSocket-Version'))) {
-            return new Response(426, ['Sec-WebSocket-Version' => $this->getVersionNumber()]);
+            return new Response(426, $upgradeSuggestion);
         }
 
         $headers = [];
@@ -81,7 +89,7 @@ class ServerNegotiator implements NegotiatorInterface {
             }, null);
 
             if ($this->_strictSubProtocols && null === $match) {
-                return new Response(400, [], '1.1', null ,'No Sec-WebSocket-Protocols requested supported');
+                return new Response(426, $upgradeSuggestion, null, '1.1', 'No Sec-WebSocket-Protocols requested supported');
             }
 
             if (null !== $match) {
@@ -107,6 +115,9 @@ class ServerNegotiator implements NegotiatorInterface {
         return base64_encode(sha1($key . static::GUID, true));
     }
 
+    /**
+     * @param array $protocols
+     */
     function setSupportedSubProtocols(array $protocols) {
         $this->_supportedSubProtocols = array_flip($protocols);
     }
diff --git a/tests/unit/Handshake/ServerNegotiatorTest.php b/tests/unit/Handshake/ServerNegotiatorTest.php
new file mode 100644
index 0000000..9c9aa8d
--- /dev/null
+++ b/tests/unit/Handshake/ServerNegotiatorTest.php
@@ -0,0 +1,175 @@
+<?php
+
+namespace Ratchet\RFC6455\Test\Unit\Handshake;
+
+use Ratchet\RFC6455\Handshake\RequestVerifier;
+use Ratchet\RFC6455\Handshake\ServerNegotiator;
+
+class ServerNegotiatorTest extends \PHPUnit_Framework_TestCase
+{
+    public function testNoUpgradeRequested() {
+        $negotiator = new ServerNegotiator(new RequestVerifier());
+
+        $requestText = 'GET / HTTP/1.1
+Host: 127.0.0.1:6789
+Connection: keep-alive
+Pragma: no-cache
+Cache-Control: no-cache
+Upgrade-Insecure-Requests: 1
+User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.133 Safari/537.36
+Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
+Accept-Encoding: gzip, deflate, sdch, br
+Accept-Language: en-US,en;q=0.8';
+
+        $request = \GuzzleHttp\Psr7\parse_request($requestText);
+
+        $response = $negotiator->handshake($request);
+
+        $this->assertEquals('1.1', $response->getProtocolVersion());
+        $this->assertEquals(426, $response->getStatusCode());
+        $this->assertEquals('Upgrade header MUST be provided', $response->getReasonPhrase());
+        $this->assertEquals('Upgrade', $response->getHeaderLine('Connection'));
+        $this->assertEquals('websocket', $response->getHeaderLine('Upgrade'));
+        $this->assertEquals('13', $response->getHeaderLine('Sec-WebSocket-Version'));
+    }
+
+    public function testNoConnectionUpgradeRequested() {
+        $negotiator = new ServerNegotiator(new RequestVerifier());
+
+        $requestText = 'GET / HTTP/1.1
+Host: 127.0.0.1:6789
+Connection: keep-alive
+Pragma: no-cache
+Cache-Control: no-cache
+Upgrade: websocket
+Upgrade-Insecure-Requests: 1
+User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.133 Safari/537.36
+Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
+Accept-Encoding: gzip, deflate, sdch, br
+Accept-Language: en-US,en;q=0.8';
+
+        $request = \GuzzleHttp\Psr7\parse_request($requestText);
+
+        $response = $negotiator->handshake($request);
+
+        $this->assertEquals('1.1', $response->getProtocolVersion());
+        $this->assertEquals(400, $response->getStatusCode());
+        $this->assertEquals('Connection Upgrade MUST be requested', $response->getReasonPhrase());
+    }
+
+    public function testInvalidSecWebsocketKey() {
+        $negotiator = new ServerNegotiator(new RequestVerifier());
+
+        $requestText = 'GET / HTTP/1.1
+Host: 127.0.0.1:6789
+Connection: Upgrade
+Pragma: no-cache
+Cache-Control: no-cache
+Upgrade: websocket
+Sec-WebSocket-Key: 12345
+Upgrade-Insecure-Requests: 1
+User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.133 Safari/537.36
+Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
+Accept-Encoding: gzip, deflate, sdch, br
+Accept-Language: en-US,en;q=0.8';
+
+        $request = \GuzzleHttp\Psr7\parse_request($requestText);
+
+        $response = $negotiator->handshake($request);
+
+        $this->assertEquals('1.1', $response->getProtocolVersion());
+        $this->assertEquals(400, $response->getStatusCode());
+        $this->assertEquals('Invalid Sec-WebSocket-Key', $response->getReasonPhrase());
+    }
+
+    public function testInvalidSecWebsocketVersion() {
+        $negotiator = new ServerNegotiator(new RequestVerifier());
+
+        $requestText = 'GET / HTTP/1.1
+Host: 127.0.0.1:6789
+Connection: Upgrade
+Pragma: no-cache
+Cache-Control: no-cache
+Upgrade: websocket
+Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
+Upgrade-Insecure-Requests: 1
+User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.133 Safari/537.36
+Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
+Accept-Encoding: gzip, deflate, sdch, br
+Accept-Language: en-US,en;q=0.8';
+
+        $request = \GuzzleHttp\Psr7\parse_request($requestText);
+
+        $response = $negotiator->handshake($request);
+
+        $this->assertEquals('1.1', $response->getProtocolVersion());
+        $this->assertEquals(426, $response->getStatusCode());
+        $this->assertEquals('Upgrade Required', $response->getReasonPhrase());
+        $this->assertEquals('Upgrade', $response->getHeaderLine('Connection'));
+        $this->assertEquals('websocket', $response->getHeaderLine('Upgrade'));
+        $this->assertEquals('13', $response->getHeaderLine('Sec-WebSocket-Version'));
+    }
+
+    public function testBadSubprotocolResponse() {
+        $negotiator = new ServerNegotiator(new RequestVerifier());
+        $negotiator->setStrictSubProtocolCheck(true);
+        $negotiator->setSupportedSubProtocols([]);
+
+        $requestText = 'GET / HTTP/1.1
+Host: 127.0.0.1:6789
+Connection: Upgrade
+Pragma: no-cache
+Cache-Control: no-cache
+Upgrade: websocket
+Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
+Sec-WebSocket-Version: 13
+Sec-WebSocket-Protocol: someprotocol
+Upgrade-Insecure-Requests: 1
+User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.133 Safari/537.36
+Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
+Accept-Encoding: gzip, deflate, sdch, br
+Accept-Language: en-US,en;q=0.8';
+
+        $request = \GuzzleHttp\Psr7\parse_request($requestText);
+
+        $response = $negotiator->handshake($request);
+
+        $this->assertEquals('1.1', $response->getProtocolVersion());
+        $this->assertEquals(426, $response->getStatusCode());
+        $this->assertEquals('No Sec-WebSocket-Protocols requested supported', $response->getReasonPhrase());
+        $this->assertEquals('Upgrade', $response->getHeaderLine('Connection'));
+        $this->assertEquals('websocket', $response->getHeaderLine('Upgrade'));
+        $this->assertEquals('13', $response->getHeaderLine('Sec-WebSocket-Version'));
+    }
+
+    public function testNonStrictSubprotocolDoesNotIncludeHeaderWhenNoneAgreedOn() {
+        $negotiator = new ServerNegotiator(new RequestVerifier());
+        $negotiator->setStrictSubProtocolCheck(false);
+        $negotiator->setSupportedSubProtocols(['someproto']);
+
+        $requestText = 'GET / HTTP/1.1
+Host: 127.0.0.1:6789
+Connection: Upgrade
+Pragma: no-cache
+Cache-Control: no-cache
+Upgrade: websocket
+Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
+Sec-WebSocket-Version: 13
+Sec-WebSocket-Protocol: someotherproto
+Upgrade-Insecure-Requests: 1
+User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.133 Safari/537.36
+Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
+Accept-Encoding: gzip, deflate, sdch, br
+Accept-Language: en-US,en;q=0.8';
+
+        $request = \GuzzleHttp\Psr7\parse_request($requestText);
+
+        $response = $negotiator->handshake($request);
+
+        $this->assertEquals('1.1', $response->getProtocolVersion());
+        $this->assertEquals(101, $response->getStatusCode());
+        $this->assertEquals('Upgrade', $response->getHeaderLine('Connection'));
+        $this->assertEquals('websocket', $response->getHeaderLine('Upgrade'));
+        $this->assertFalse($response->hasHeader('Sec-WebSocket-Protocol'));
+    }
+}
\ No newline at end of file