diff --git a/README.md b/README.md
index b3b8e2660..3555b52b3 100644
--- a/README.md
+++ b/README.md
@@ -50,8 +50,9 @@ Model Usage
 You can also use the library in an object oriented manner.
 
 ```php
-$client = new \Gitlab\Client('http://git.yourdomain.com/api/v3/'); // change here
-$client->authenticate('your_gitlab_token_here', \Gitlab\Client::AUTH_URL_TOKEN); // change here
+$guzzle = new \Gitlab\HttpClient\Adapter\Guzzle4();
+$client = new \Gitlab\Client('http://git.yourdomain.com/api/v3/', $guzzle); // change here
+$client->authenticate('your_gitlab_token_here', \Gitlab\HttpClient\HttpClientInterface::AUTH_URL_TOKEN); // change here
 ```
 
 Creating a new project
diff --git a/composer.json b/composer.json
index 5002c8af5..2ae050323 100644
--- a/composer.json
+++ b/composer.json
@@ -21,10 +21,12 @@
 		}
 	],
 	"require": {
-		"php":                ">=5.3.2",
-		"ext-curl":           "*",
-		"kriswallsmith/buzz": ">=0.7"
+		"php":                ">=5.3.2"
 	},
+    "suggest": {
+        "kriswallsmith/buzz": "To use Buzz as the HTTP adapter (~0.7)",
+        "guzzlehttp/guzzle": "To use Guzzle as the HTTP adapter (~3.7, ~4.1)"
+    },
 	"autoload": {
 		"psr-0": { "Gitlab\\": "lib/" }
 	}
diff --git a/lib/Gitlab/Api/AbstractApi.php b/lib/Gitlab/Api/AbstractApi.php
index 63632a3f9..2645e915a 100644
--- a/lib/Gitlab/Api/AbstractApi.php
+++ b/lib/Gitlab/Api/AbstractApi.php
@@ -40,7 +40,7 @@ public function configure()
      */
     protected function get($path, array $parameters = array(), $requestHeaders = array())
     {
-        $response = $this->client->getHttpClient()->get($path, $parameters, $requestHeaders);
+        $response = $this->client->get($path, $parameters, $requestHeaders);
 
         return $response->getContent();
     }
@@ -50,7 +50,7 @@ protected function get($path, array $parameters = array(), $requestHeaders = arr
      */
     protected function post($path, array $parameters = array(), $requestHeaders = array())
     {
-        $response = $this->client->getHttpClient()->post($path, $parameters, $requestHeaders);
+        $response = $this->client->post($path, $parameters, $requestHeaders);
 
         return $response->getContent();
     }
@@ -60,7 +60,7 @@ protected function post($path, array $parameters = array(), $requestHeaders = ar
      */
     protected function patch($path, array $parameters = array(), $requestHeaders = array())
     {
-        $response = $this->client->getHttpClient()->patch($path, $parameters, $requestHeaders);
+        $response = $this->client->patch($path, $parameters, $requestHeaders);
 
         return $response->getContent();
     }
@@ -70,7 +70,7 @@ protected function patch($path, array $parameters = array(), $requestHeaders = a
      */
     protected function put($path, array $parameters = array(), $requestHeaders = array())
     {
-        $response = $this->client->getHttpClient()->put($path, $parameters, $requestHeaders);
+        $response = $this->client->put($path, $parameters, $requestHeaders);
 
         return $response->getContent();
     }
@@ -80,7 +80,7 @@ protected function put($path, array $parameters = array(), $requestHeaders = arr
      */
     protected function delete($path, array $parameters = array(), $requestHeaders = array())
     {
-        $response = $this->client->getHttpClient()->delete($path, $parameters, $requestHeaders);
+        $response = $this->client->delete($path, $parameters, $requestHeaders);
 
         return $response->getContent();
     }
diff --git a/lib/Gitlab/Client.php b/lib/Gitlab/Client.php
index 373da4820..e6e87b143 100644
--- a/lib/Gitlab/Client.php
+++ b/lib/Gitlab/Client.php
@@ -2,32 +2,16 @@
 
 namespace Gitlab;
 
-use Buzz\Client\Curl;
-use Buzz\Client\ClientInterface;
-
 use Gitlab\Api\ApiInterface;
 use Gitlab\Exception\InvalidArgumentException;
+use Gitlab\HttpClient\Adapter\AdapterInterface;
 use Gitlab\HttpClient\HttpClient;
-use Gitlab\HttpClient\HttpClientInterface;
-use Gitlab\HttpClient\Listener\AuthListener;
 
 /**
  * Simple API wrapper for Gitlab
  */
 class Client
 {
-    /**
-     * Constant for authentication method. Indicates the default, but deprecated
-     * login with username and token in URL.
-     */
-    const AUTH_URL_TOKEN = 'url_token';
-
-    /**
-     * Constant for authentication method. Indicates the new login method with
-     * with username and token via HTTP Authentication.
-     */
-    const AUTH_HTTP_TOKEN = 'http_token';
-
     /**
      * @var array
      */
@@ -36,10 +20,8 @@ class Client
         'timeout'     => 60
     );
 
-    private $base_url = null;
-
     /**
-     * The Buzz instance used to communicate with Gitlab
+     * The HTTP client instance used to communicate with Gitlab
      *
      * @var HttpClient
      */
@@ -48,17 +30,12 @@ class Client
     /**
      * Instantiate a new Gitlab client
      *
-     * @param string               $baseUrl
-     * @param null|ClientInterface $httpClient Buzz client
+     * @param string           $baseUrl
+     * @param AdapterInterface $adapter
      */
-    public function __construct($baseUrl, ClientInterface $httpClient = null)
+    public function __construct($baseUrl, AdapterInterface $adapter)
     {
-        $httpClient = $httpClient ?: new Curl();
-        $httpClient->setTimeout($this->options['timeout']);
-        $httpClient->setVerifyPeer(false);
-
-        $this->base_url     = $baseUrl;
-        $this->httpClient   = new HttpClient($this->base_url, $this->options, $httpClient);
+        $this->httpClient = new HttpClient($baseUrl, $adapter);
     }
 
     /**
@@ -131,38 +108,32 @@ public function api($name)
      */
     public function authenticate($token, $authMethod = null, $sudo = null)
     {
-        $this->httpClient->addListener(
-            new AuthListener(
-                $authMethod,
-                $token,
-                $sudo
-            )
-        );
+        $this->httpClient->authenticate($token, $authMethod, $sudo);
     }
 
-    /**
-     * @return HttpClient
-     */
-    public function getHttpClient()
+    public function get($path, array $parameters = array(), array $headers = array())
     {
-        return $this->httpClient;
+        return $this->httpClient->get($path, $parameters, $headers);
     }
 
-    /**
-     * @param HttpClientInterface $httpClient
-     */
-    public function setHttpClient(HttpClientInterface $httpClient)
+    public function post($path, array $parameters = array(), array $headers = array())
     {
-        $this->httpClient = $httpClient;
+        return $this->httpClient->post($path, $parameters, $headers);
     }
 
-    public function setBaseUrl($url)
+    public function patch($path, array $parameters = array(), array $headers = array())
     {
-        $this->base_url = $url;
+        return $this->httpClient->patch($path, $parameters, $headers);
     }
-    public function getBaseUrl()
+
+    public function delete($path, array $parameters = array(), array $headers = array())
+    {
+        return $this->httpClient->delete($path, $parameters, $headers);
+    }
+
+    public function put($path, array $parameters = array(), array $headers = array())
     {
-        return $this->base_url;
+        return $this->httpClient->put($path, $parameters, $headers);
     }
 
     /**
diff --git a/lib/Gitlab/HttpClient/Adapter/AdapterInterface.php b/lib/Gitlab/HttpClient/Adapter/AdapterInterface.php
new file mode 100644
index 000000000..9dc1b9c79
--- /dev/null
+++ b/lib/Gitlab/HttpClient/Adapter/AdapterInterface.php
@@ -0,0 +1,9 @@
+<?php
+namespace Gitlab\HttpClient\Adapter;
+
+interface AdapterInterface
+{
+    public function request($path, array $parameters = array(), $httpMethod = 'GET', array $headers = array());
+
+    public function authenticate($token, $authMethod, $sudo = null);
+}
diff --git a/lib/Gitlab/HttpClient/Adapter/BuzzAdapter.php b/lib/Gitlab/HttpClient/Adapter/BuzzAdapter.php
new file mode 100644
index 000000000..3ce200402
--- /dev/null
+++ b/lib/Gitlab/HttpClient/Adapter/BuzzAdapter.php
@@ -0,0 +1,119 @@
+<?php
+namespace Gitlab\HttpClient\Adapter;
+
+use Buzz\Client\AbstractClient;
+use Buzz\Client\Curl;
+use Buzz\Listener\ListenerInterface;
+use Gitlab\Exception\ErrorException;
+use Gitlab\Exception\RuntimeException;
+use Gitlab\HttpClient\Listener\AuthListener;
+use Gitlab\HttpClient\Listener\ErrorListener;
+use Gitlab\HttpClient\Message\Request;
+use Gitlab\HttpClient\Message\BuzzResponse;
+
+class BuzzAdapter implements AdapterInterface
+{
+    /**
+     * @var AbstractClient
+     */
+    protected $client;
+
+    /**
+     * @var ListenerInterface[]
+     */
+    protected $listeners = array();
+
+    /**
+     * @param AbstractClient $client
+     */
+    public function __construct(AbstractClient $client = null)
+    {
+        $this->client = $client ?: new Curl();
+
+        $this->addListener(new ErrorListener());
+    }
+
+    /**
+     * @param int $timeout
+     *
+     * @return $this
+     */
+    public function setTimeout($timeout)
+    {
+        $this->client->setTimeout($timeout);
+
+        return $this;
+    }
+
+    /**
+     * @param bool $verify
+     *
+     * @return $this
+     */
+    public function verifyPeer($verify)
+    {
+        $this->client->setVerifyPeer($verify);
+
+        return $this;
+    }
+
+    /**
+     * @param string $path
+     * @param array  $parameters
+     * @param string $httpMethod
+     * @param array  $headers
+     *
+     * @throws ErrorException
+     * @throws RuntimeException
+     *
+     * @return BuzzResponse
+     */
+    public function request($path, array $parameters = array(), $httpMethod = 'GET', array $headers = array())
+    {
+        $request = new Request($httpMethod);
+        $request->setHeaders($headers);
+        $request->fromUrl($path);
+        $request->setContent(http_build_query($parameters));
+
+        $hasListeners = 0 < count($this->listeners);
+        if ($hasListeners) {
+            foreach ($this->listeners as $listener) {
+                $listener->preSend($request);
+            }
+        }
+
+        $response = new BuzzResponse();
+
+        try {
+            $this->client->send($request, $response);
+        } catch (\LogicException $e) {
+            throw new ErrorException($e->getMessage(), $e->getCode(), $e);
+        } catch (\RuntimeException $e) {
+            throw new RuntimeException($e->getMessage(), $e->getCode(), $e);
+        }
+
+        if ($hasListeners) {
+            foreach ($this->listeners as $listener) {
+                $listener->postSend($request, $response);
+            }
+        }
+
+        return $response;
+    }
+
+    public function authenticate($token, $authMethod, $sudo = null)
+    {
+        $this->addListener(
+            new AuthListener(
+                $authMethod,
+                $token,
+                $sudo
+            )
+        );
+    }
+
+    public function addListener(ListenerInterface $listener)
+    {
+        $this->listeners[get_class($listener)] = $listener;
+    }
+}
diff --git a/lib/Gitlab/HttpClient/Adapter/Guzzle3Adapter.php b/lib/Gitlab/HttpClient/Adapter/Guzzle3Adapter.php
new file mode 100644
index 000000000..d5275bb06
--- /dev/null
+++ b/lib/Gitlab/HttpClient/Adapter/Guzzle3Adapter.php
@@ -0,0 +1,56 @@
+<?php
+namespace Gitlab\HttpClient\Adapter;
+
+use Gitlab\Exception\ErrorException;
+use Gitlab\Exception\RuntimeException;
+use Gitlab\HttpClient\Message\Guzzle3Response;
+use Gitlab\HttpClient\Subscriber\AuthSubscriber;
+use Guzzle\Http\Client;
+use Guzzle\Http\ClientInterface;
+
+class Guzzle3Adapter implements AdapterInterface
+{
+    /**
+     * @var ClientInterface
+     */
+    protected $client;
+
+    /**
+     * @param ClientInterface $client
+     */
+    public function __construct(ClientInterface $client = null)
+    {
+        $this->client = $client ?: new Client();
+    }
+
+    /**
+     * @param string $path
+     * @param array  $parameters
+     * @param string $httpMethod
+     * @param array  $headers
+     *
+     * @throws ErrorException
+     * @throws RuntimeException
+     *
+     * @return Guzzle3Response
+     */
+    public function request($path, array $parameters = array(), $httpMethod = 'GET', array $headers = array())
+    {
+        $request = $this->client->createRequest($httpMethod, $path, $headers, http_build_query($parameters));
+
+        try {
+            $response = $this->client->send($request);
+        } catch (\LogicException $e) {
+            throw new ErrorException($e->getMessage(), $e->getCode(), $e);
+        } catch (\RuntimeException $e) {
+            throw new RuntimeException($e->getMessage(), $e->getCode(), $e);
+        }
+
+        return new Guzzle3Response($response);
+    }
+
+    public function authenticate($token, $authMethod, $sudo = null)
+    {
+        $this->client->addSubscriber(new AuthSubscriber($authMethod, $token, $sudo));
+    }
+}
diff --git a/lib/Gitlab/HttpClient/Adapter/Guzzle4Adapter.php b/lib/Gitlab/HttpClient/Adapter/Guzzle4Adapter.php
new file mode 100644
index 000000000..60ce8a907
--- /dev/null
+++ b/lib/Gitlab/HttpClient/Adapter/Guzzle4Adapter.php
@@ -0,0 +1,56 @@
+<?php
+namespace Gitlab\HttpClient\Adapter;
+
+use Gitlab\Exception\ErrorException;
+use Gitlab\Exception\RuntimeException;
+use Gitlab\HttpClient\Message\Guzzle4Response;
+use Gitlab\HttpClient\Subscriber\AuthSubscriber;
+use GuzzleHttp\Client;
+use GuzzleHttp\ClientInterface;
+
+class Guzzle4Adapter implements AdapterInterface
+{
+    /**
+     * @var ClientInterface
+     */
+    protected $client;
+
+    /**
+     * @param ClientInterface $client
+     */
+    public function __construct(ClientInterface $client = null)
+    {
+        $this->client = $client ?: new Client();
+    }
+
+    /**
+     * @param string $path
+     * @param array  $parameters
+     * @param string $httpMethod
+     * @param array  $headers
+     *
+     * @throws ErrorException
+     * @throws RuntimeException
+     *
+     * @return Guzzle4Response
+     */
+    public function request($path, array $parameters = array(), $httpMethod = 'GET', array $headers = array())
+    {
+        $request = $this->client->createRequest($httpMethod, $path, $headers, http_build_query($parameters));
+
+        try {
+            $response = $this->client->send($request);
+        } catch (\LogicException $e) {
+            throw new ErrorException($e->getMessage(), $e->getCode(), $e);
+        } catch (\RuntimeException $e) {
+            throw new RuntimeException($e->getMessage(), $e->getCode(), $e);
+        }
+
+        return new Guzzle4Response($response);
+    }
+
+    public function authenticate($token, $authMethod, $sudo = null)
+    {
+        $this->client->getEmitter()->attach(new AuthSubscriber($authMethod, $token, $sudo));
+    }
+}
diff --git a/lib/Gitlab/HttpClient/HttpClient.php b/lib/Gitlab/HttpClient/HttpClient.php
index c0a33bcb0..deb649fcc 100644
--- a/lib/Gitlab/HttpClient/HttpClient.php
+++ b/lib/Gitlab/HttpClient/HttpClient.php
@@ -2,14 +2,7 @@
 
 namespace Gitlab\HttpClient;
 
-use Buzz\Client\ClientInterface;
-use Buzz\Listener\ListenerInterface;
-
-use Gitlab\Exception\ErrorException;
-use Gitlab\Exception\RuntimeException;
-use Gitlab\HttpClient\Listener\ErrorListener;
-use Gitlab\HttpClient\Message\Request;
-use Gitlab\HttpClient\Message\Response;
+use Gitlab\HttpClient\Adapter\AdapterInterface;
 
 /**
  * Performs requests on Gitlab API. API documentation should be self-explanatory.
@@ -19,48 +12,30 @@
 class HttpClient implements HttpClientInterface
 {
     /**
-     * @var array
+     * @var string
      */
-    protected $options = array(
-        'user_agent'  => 'php-gitlab-api (http://github.com/m4tthumphrey/php-gitlab-api)',
-        'timeout'     => 10,
-    );
-
-    protected $base_url = null;
+    protected $baseUrl;
 
-    /**
-     * @var array
-     */
-    protected $listeners = array();
     /**
      * @var array
      */
     protected $headers = array();
 
-    private $lastResponse;
-    private $lastRequest;
-
     /**
-     * @param array           $options
-     * @param ClientInterface $client
+     * @var AdapterInterface
      */
-    public function __construct($baseUrl, array $options, ClientInterface $client)
-    {
-        $this->base_url = $baseUrl;
-        $this->options  = array_merge($this->options, $options);
-        $this->client   = $client;
-
-        $this->addListener(new ErrorListener($this->options));
-
-        $this->clearHeaders();
-    }
+    protected $adapter;
 
     /**
-     * {@inheritDoc}
+     * @param string           $baseUrl
+     * @param AdapterInterface $adapter
      */
-    public function setOption($name, $value)
+    public function __construct($baseUrl, AdapterInterface $adapter)
     {
-        $this->options[$name] = $value;
+        $this->baseUrl = $baseUrl;
+        $this->adapter = $adapter;
+
+        $this->clearHeaders();
     }
 
     /**
@@ -79,21 +54,13 @@ public function clearHeaders()
         $this->headers = array();
     }
 
-    /**
-     * @param ListenerInterface $listener
-     */
-    public function addListener(ListenerInterface $listener)
-    {
-        $this->listeners[get_class($listener)] = $listener;
-    }
-
     /**
      * {@inheritDoc}
      */
     public function get($path, array $parameters = array(), array $headers = array())
     {
         if (0 < count($parameters)) {
-            $path .= (false === strpos($path, '?') ? '?' : '&').http_build_query($parameters, '', '&');
+            $path .= (false === strpos($path, '?') ? '?' : '&') . http_build_query($parameters, '', '&');
         }
 
         return $this->request($path, array(), 'GET', $headers);
@@ -136,69 +103,14 @@ public function put($path, array $parameters = array(), array $headers = array()
      */
     public function request($path, array $parameters = array(), $httpMethod = 'GET', array $headers = array())
     {
-        $path = trim($this->base_url.$path, '/');
-
-        $request = $this->createRequest($httpMethod, $path);
-        $request->addHeaders($headers);
-        $request->setContent(http_build_query($parameters));
-
-        $hasListeners = 0 < count($this->listeners);
-        if ($hasListeners) {
-            foreach ($this->listeners as $listener) {
-                $listener->preSend($request);
-            }
-        }
-
-        $response = new Response();
-
-        try {
-            $this->client->send($request, $response);
-        } catch (\LogicException $e) {
-            throw new ErrorException($e->getMessage());
-        } catch (\RuntimeException $e) {
-            throw new RuntimeException($e->getMessage());
-        }
-
-        $this->lastRequest  = $request;
-        $this->lastResponse = $response;
-
-        if ($hasListeners) {
-            foreach ($this->listeners as $listener) {
-                $listener->postSend($request, $response);
-            }
-        }
-
-        return $response;
-    }
-
-    /**
-     * @return Request
-     */
-    public function getLastRequest()
-    {
-        return $this->lastRequest;
-    }
+        $path = '/' . trim($path, '/') . '/';
+        $headers = array_merge($this->headers, $headers);
 
-    /**
-     * @return Response
-     */
-    public function getLastResponse()
-    {
-        return $this->lastResponse;
+        return $this->adapter->request($this->baseUrl . $path, $parameters, $httpMethod, $headers);
     }
 
-    /**
-     * @param string $httpMethod
-     * @param string $url
-     *
-     * @return Request
-     */
-    private function createRequest($httpMethod, $url)
+    public function authenticate($token, $authMethod = null, $sudo = null)
     {
-        $request = new Request($httpMethod);
-        $request->setHeaders($this->headers);
-        $request->fromUrl($url);
-
-        return $request;
+        $this->adapter->authenticate($token, $authMethod, $sudo);
     }
 }
diff --git a/lib/Gitlab/HttpClient/HttpClientInterface.php b/lib/Gitlab/HttpClient/HttpClientInterface.php
index 75699a2f9..9c43b3b17 100644
--- a/lib/Gitlab/HttpClient/HttpClientInterface.php
+++ b/lib/Gitlab/HttpClient/HttpClientInterface.php
@@ -1,8 +1,7 @@
 <?php
 
 namespace Gitlab\HttpClient;
-
-use Gitlab\Exception\InvalidArgumentException;
+use Gitlab\HttpClient\Message\ResponseInterface;
 
 /**
  * Performs requests on Gitlab API. API documentation should be self-explanatory.
@@ -11,6 +10,18 @@
  */
 interface HttpClientInterface
 {
+    /**
+     * Constant for authentication method. Indicates the default, but deprecated
+     * login with username and token in URL.
+     */
+    const AUTH_URL_TOKEN = 'url_token';
+
+    /**
+     * Constant for authentication method. Indicates the new login method with
+     * with username and token via HTTP Authentication.
+     */
+    const AUTH_HTTP_TOKEN = 'http_token';
+
     /**
      * Send a GET request
      *
@@ -18,7 +29,7 @@ interface HttpClientInterface
      * @param array  $parameters GET Parameters
      * @param array  $headers    Reconfigure the request headers for this call only
      *
-     * @return array Data
+     * @return array ResponseInterface
      */
     public function get($path, array $parameters = array(), array $headers = array());
 
@@ -29,7 +40,7 @@ public function get($path, array $parameters = array(), array $headers = array()
      * @param array  $parameters POST Parameters
      * @param array  $headers    Reconfigure the request headers for this call only
      *
-     * @return array Data
+     * @return array ResponseInterface
      */
     public function post($path, array $parameters = array(), array $headers = array());
 
@@ -40,7 +51,7 @@ public function post($path, array $parameters = array(), array $headers = array(
      * @param array  $parameters PATCH Parameters
      * @param array  $headers    Reconfigure the request headers for this call only
      *
-     * @return array Data
+     * @return array ResponseInterface
      */
     public function patch($path, array $parameters = array(), array $headers = array());
 
@@ -51,7 +62,7 @@ public function patch($path, array $parameters = array(), array $headers = array
      * @param array  $parameters PUT Parameters
      * @param array  $headers    Reconfigure the request headers for this call only
      *
-     * @return array Data
+     * @return array ResponseInterface
      */
     public function put($path, array $parameters = array(), array $headers = array());
 
@@ -62,7 +73,7 @@ public function put($path, array $parameters = array(), array $headers = array()
      * @param array  $parameters DELETE Parameters
      * @param array  $headers    Reconfigure the request headers for this call only
      *
-     * @return array Data
+     * @return array ResponseInterface
      */
     public function delete($path, array $parameters = array(), array $headers = array());
 
@@ -75,19 +86,18 @@ public function delete($path, array $parameters = array(), array $headers = arra
      * @param string $httpMethod HTTP method to use
      * @param array  $headers    Request headers
      *
-     * @return array Data
+     * @return ResponseInterface
      */
     public function request($path, array $parameters = array(), $httpMethod = 'GET', array $headers = array());
 
     /**
-     * Change an option value.
-     *
-     * @param string $name  The option name
-     * @param mixed  $value The value
+     * Authenticate a user for all next requests
      *
-     * @throws InvalidArgumentException
+     * @param string      $token      Gitlab private token
+     * @param null|string $authMethod One of the AUTH_* class constants
+     * @param null|string $sudo
      */
-    public function setOption($name, $value);
+    public function authenticate($token, $authMethod = null, $sudo = null);
 
     /**
      * Set HTTP headers
diff --git a/lib/Gitlab/HttpClient/Listener/AuthListener.php b/lib/Gitlab/HttpClient/Listener/AuthListener.php
index b147fb4e8..ef29fcdde 100644
--- a/lib/Gitlab/HttpClient/Listener/AuthListener.php
+++ b/lib/Gitlab/HttpClient/Listener/AuthListener.php
@@ -2,13 +2,11 @@
 
 namespace Gitlab\HttpClient\Listener;
 
-use Gitlab\Client;
+use Buzz\Message\RequestInterface;
 use Gitlab\Exception\InvalidArgumentException;
-
 use Buzz\Listener\ListenerInterface;
 use Buzz\Message\MessageInterface;
-use Buzz\Message\RequestInterface;
-use Buzz\Util\Url;
+use Gitlab\HttpClient\HttpClientInterface;
 
 /**
  * @author Joseph Bielawski <stloyd@gmail.com>
@@ -49,28 +47,25 @@ public function __construct($method, $token, $sudo = null)
      */
     public function preSend(RequestInterface $request)
     {
-        // Skip by default
-        if (null === $this->method) {
-            return;
-        }
-
         switch ($this->method) {
-            case Client::AUTH_HTTP_TOKEN:
-                $request->addHeader('PRIVATE-TOKEN: '.$this->token);
+            case HttpClientInterface::AUTH_HTTP_TOKEN:
+                $request->addHeader('PRIVATE-TOKEN:' . $this->token);
                 if (!is_null($this->sudo)) {
-                    $request->addHeader('SUDO: '.$this->sudo);
+                    $request->addHeader('SUDO:' . $this->sudo);
                 }
                 break;
 
-            case Client::AUTH_URL_TOKEN:
-                $url  = $request->getUrl();
-                $query=array('private_token' => $this->token);
+            case HttpClientInterface::AUTH_URL_TOKEN:
+                $url = $request->getUrl();
+                $query = array('private_token' => $this->token);
+
                 if (!is_null($this->sudo)) {
                     $query['sudo'] = $this->sudo;
                 }
+
                 $url .= (false === strpos($url, '?') ? '?' : '&').utf8_encode(http_build_query($query, '', '&'));
 
-                $request->fromUrl(new Url($url));
+                $request->setUrl($url);
                 break;
         }
     }
diff --git a/lib/Gitlab/HttpClient/Listener/ErrorListener.php b/lib/Gitlab/HttpClient/Listener/ErrorListener.php
index eb47abf75..9238ebb98 100644
--- a/lib/Gitlab/HttpClient/Listener/ErrorListener.php
+++ b/lib/Gitlab/HttpClient/Listener/ErrorListener.php
@@ -13,19 +13,6 @@
  */
 class ErrorListener implements ListenerInterface
 {
-    /**
-     * @var array
-     */
-    private $options;
-
-    /**
-     * @param array $options
-     */
-    public function __construct(array $options)
-    {
-        $this->options = $options;
-    }
-
     /**
      * {@inheritDoc}
      */
@@ -38,7 +25,7 @@ public function preSend(RequestInterface $request)
      */
     public function postSend(RequestInterface $request, MessageInterface $response)
     {
-        /** @var $response \Gitlab\HttpClient\Message\Response */
+        /** @var $response \Gitlab\HttpClient\Message\BuzzResponse */
         if ($response->isClientError() || $response->isServerError()) {
             $content = $response->getContent();
             if (is_array($content) && isset($content['message'])) {
diff --git a/lib/Gitlab/HttpClient/Message/Response.php b/lib/Gitlab/HttpClient/Message/BuzzResponse.php
similarity index 63%
rename from lib/Gitlab/HttpClient/Message/Response.php
rename to lib/Gitlab/HttpClient/Message/BuzzResponse.php
index 49228f32f..c40cb00fe 100644
--- a/lib/Gitlab/HttpClient/Message/Response.php
+++ b/lib/Gitlab/HttpClient/Message/BuzzResponse.php
@@ -4,7 +4,7 @@
 
 use Buzz\Message\Response as BaseResponse;
 
-class Response extends BaseResponse
+class BuzzResponse extends BaseResponse implements ResponseInterface
 {
     /**
      * {@inheritDoc}
@@ -12,16 +12,15 @@ class Response extends BaseResponse
     public function getContent()
     {
         $response = parent::getContent();
+
         if ($this->getHeader("Content-Type") === "application/json") {
             $content  = json_decode($response, true);
-    
-            if (JSON_ERROR_NONE !== json_last_error()) {
-                return $response;
+
+            if (JSON_ERROR_NONE === json_last_error()) {
+                return $content;
             }
-    
-            return $content;
-        } else {
-            return $response;
         }
+
+        return $response;
     }
 }
diff --git a/lib/Gitlab/HttpClient/Message/Guzzle3Response.php b/lib/Gitlab/HttpClient/Message/Guzzle3Response.php
new file mode 100644
index 000000000..7d0287520
--- /dev/null
+++ b/lib/Gitlab/HttpClient/Message/Guzzle3Response.php
@@ -0,0 +1,33 @@
+<?php
+
+namespace Gitlab\HttpClient\Message;
+
+use Guzzle\Http\Message;
+
+class Guzzle3Response implements ResponseInterface
+{
+    protected $response;
+
+    public function __construct(Message\Response $response)
+    {
+        $this->response = $response;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function getContent()
+    {
+        $response = $this->response->getBody(true);
+
+        if ($this->response->getHeader("Content-Type")->hasValue("application/json")) {
+            $content  = json_decode($response, true);
+
+            if (JSON_ERROR_NONE === json_last_error()) {
+                return $content;
+            }
+        }
+
+        return $response;
+    }
+}
diff --git a/lib/Gitlab/HttpClient/Message/Guzzle4Response.php b/lib/Gitlab/HttpClient/Message/Guzzle4Response.php
new file mode 100644
index 000000000..008fcb443
--- /dev/null
+++ b/lib/Gitlab/HttpClient/Message/Guzzle4Response.php
@@ -0,0 +1,33 @@
+<?php
+
+namespace Gitlab\HttpClient\Message;
+
+use GuzzleHttp\Message\Response;
+
+class Guzzle4Response implements ResponseInterface
+{
+    protected $response;
+
+    public function __construct(Response $response)
+    {
+        $this->response = $response;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function getContent()
+    {
+        $response = $this->response->getBody(true);
+
+        if ($this->response->getHeader("Content-Type") === "application/json") {
+            $content  = json_decode($response, true);
+
+            if (JSON_ERROR_NONE === json_last_error()) {
+                return $content;
+            }
+        }
+
+        return $response;
+    }
+}
diff --git a/lib/Gitlab/HttpClient/Message/ResponseInterface.php b/lib/Gitlab/HttpClient/Message/ResponseInterface.php
new file mode 100644
index 000000000..1761feee1
--- /dev/null
+++ b/lib/Gitlab/HttpClient/Message/ResponseInterface.php
@@ -0,0 +1,8 @@
+<?php
+
+namespace Gitlab\HttpClient\Message;
+
+interface ResponseInterface
+{
+    public function getContent();
+}
diff --git a/lib/Gitlab/HttpClient/Subscriber/AUthSubscriber.php b/lib/Gitlab/HttpClient/Subscriber/AUthSubscriber.php
new file mode 100644
index 000000000..887c36c58
--- /dev/null
+++ b/lib/Gitlab/HttpClient/Subscriber/AUthSubscriber.php
@@ -0,0 +1,87 @@
+<?php
+
+namespace Gitlab\HttpClient\Subscriber;
+
+use Gitlab\Exception\InvalidArgumentException;
+use Gitlab\HttpClient\HttpClientInterface;
+use Guzzle\Common\Event;
+use Guzzle\Http\Message\Request;
+use GuzzleHttp\Event\BeforeEvent;
+use GuzzleHttp\Event\SubscriberInterface;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+
+class AuthSubscriber implements EventSubscriberInterface, SubscriberInterface
+{
+    /**
+     * @var string
+     */
+    private $method;
+
+    /**
+     * @var string
+     */
+    private $token;
+
+    /**
+     * @var string|null
+     */
+    private $sudo;
+
+    /**
+     * @param string      $method
+     * @param string      $token
+     * @param string|null $sudo
+     */
+    public function __construct($method, $token, $sudo = null)
+    {
+        $this->method  = $method;
+        $this->token = $token;
+        $this->sudo = $sudo;
+    }
+
+    public static function getSubscribedEvents()
+    {
+        return array('request.before_send' => 'beforeRequest');
+    }
+
+    public function getEvents()
+    {
+        return array('before' => array('beforeRequest'));
+    }
+
+    public function beforeRequest($event)
+    {
+        if ($event instanceof Event) {
+            /**
+             * @var Request
+             */
+            $request = $event['request'];
+        } elseif ($event instanceof BeforeEvent) {
+            $request = $event->getRequest();
+        } else {
+            throw new InvalidArgumentException();
+        }
+
+        switch ($this->method) {
+            case HttpClientInterface::AUTH_HTTP_TOKEN:
+                $request->addHeader('PRIVATE-TOKEN', $this->token);
+                if (!is_null($this->sudo)) {
+                    $request->addHeader('SUDO', $this->sudo);
+                }
+                break;
+
+            case HttpClientInterface::AUTH_URL_TOKEN:
+                $url = $request->getUrl();
+                $query = array('private_token' => $this->token);
+
+                if (!is_null($this->sudo)) {
+                    $query['sudo'] = $this->sudo;
+                }
+
+                $url .= (false === strpos($url, '?') ? '?' : '&').utf8_encode(http_build_query($query, '', '&'));
+
+                $request->setUrl($url);
+                break;
+        }
+    }
+}
diff --git a/test.php b/test.php
new file mode 100644
index 000000000..e69de29bb