diff --git a/src/Handshake/ClientNegotiator.php b/src/Handshake/ClientNegotiator.php
index c393194..ca93669 100644
--- a/src/Handshake/ClientNegotiator.php
+++ b/src/Handshake/ClientNegotiator.php
@@ -5,7 +5,7 @@ use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\UriInterface;
 use GuzzleHttp\Psr7\Request;
 
-class ClientNegotiator implements ClientNegotiatorInterface {
+class ClientNegotiator {
     /**
      * @var ResponseVerifier
      */
@@ -22,7 +22,7 @@ class ClientNegotiator implements ClientNegotiatorInterface {
         $this->defaultHeader = new Request('GET', '', [
             'Connection'            => 'Upgrade'
           , 'Upgrade'               => 'websocket'
-          , 'Sec-WebSocket-Version' => 13
+          , 'Sec-WebSocket-Version' => $this->getVersion()
           , 'User-Agent'            => "RatchetRFC/0.0.0"
         ]);
     }
@@ -48,4 +48,7 @@ class ClientNegotiator implements ClientNegotiatorInterface {
         return base64_encode($key);
     }
 
-} 
\ No newline at end of file
+    public function getVersion() {
+        return 13;
+    }
+}
\ No newline at end of file
diff --git a/src/Handshake/ClientNegotiatorInterface.php b/src/Handshake/ClientNegotiatorInterface.php
deleted file mode 100644
index c95c1ac..0000000
--- a/src/Handshake/ClientNegotiatorInterface.php
+++ /dev/null
@@ -1,11 +0,0 @@
-<?php
-
-
-namespace Ratchet\RFC6455\Handshake;
-
-
-interface ClientNegotiatorInterface {
-    const GUID = '258EAFA5-E914-47DA-95CA-C5AB0DC85B11';
-
-
-} 
\ No newline at end of file
diff --git a/src/Handshake/ResponseVerifier.php b/src/Handshake/ResponseVerifier.php
index 58d05be..6fa54ae 100644
--- a/src/Handshake/ResponseVerifier.php
+++ b/src/Handshake/ResponseVerifier.php
@@ -11,15 +11,15 @@ class ResponseVerifier {
         $passes += (int)$this->verifyUpgrade($response->getHeader('Upgrade'));
         $passes += (int)$this->verifyConnection($response->getHeader('Connection'));
         $passes += (int)$this->verifySecWebSocketAccept(
-            $response->getHeader('Sec-WebSocket-Accept'),
-            $request->getHeader('sec-websocket-key')
-            );
+            $response->getHeader('Sec-WebSocket-Accept')
+          , $request->getHeader('Sec-WebSocket-Accept')
+        );
 
-        return (4 == $passes);
+        return (4 === $passes);
     }
 
     public function verifyStatus($status) {
-        return ($status == 101);
+        return ((int)$status === 101);
     }
 
     public function verifyUpgrade(array $upgrade) {
@@ -34,10 +34,10 @@ class ResponseVerifier {
         return (
             1 === count($swa) &&
             1 === count($key) &&
-            $swa[0] == $this->sign($key[0]));
+            $swa[0] === $this->sign($key[0]));
     }
 
     public function sign($key) {
-        return base64_encode(sha1($key . Negotiator::GUID, true));
+        return base64_encode(sha1($key . NegotiatorInterface::GUID, true));
     }
 }
\ No newline at end of file