diff --git a/.gitignore b/.gitignore
index 77aae3d..df26bab 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,10 @@
 /.idea
 /composer.lock
 /vendor
+/build
+/test-reports
+!.editorconfig
+!.gitattributes
+!.gitignore
+!.gitkeep
+!.php-cs-fixer.dist.php
diff --git a/composer.json b/composer.json
index 3ccfb79..08feea0 100644
--- a/composer.json
+++ b/composer.json
@@ -12,7 +12,7 @@
     }
   ],
   "require": {
-    "guzzlehttp/guzzle": "6.*"
+    "guzzlehttp/guzzle": "^6.0 || ^7.0"
   },
   "require-dev": {
     "phpunit/phpunit": "~5.7"
diff --git a/src/Lamia/HttpClient/HttpClient.php b/src/Lamia/HttpClient/HttpClient.php
index 4d4db51..7a309ce 100644
--- a/src/Lamia/HttpClient/HttpClient.php
+++ b/src/Lamia/HttpClient/HttpClient.php
@@ -15,7 +15,7 @@ class HttpClient implements HttpClientInterface
      */
     protected $client;
 
-    protected $headers = array();
+    protected $headers = [];
     private $lastResponse;
     private $lastRequest;
 
@@ -29,7 +29,7 @@ class HttpClient implements HttpClientInterface
      * @param array           $options
      * @param ClientInterface $client
      */
-    public function __construct($baseUrl, array $options = array(), ClientInterface $client = null)
+    public function __construct($baseUrl, array $options = [], ClientInterface $client = null)
     {
         $this->options = array_merge($this->options, $options);
         $this->options['base_uri'] = $baseUrl;
@@ -66,7 +66,7 @@ public function setHeaders(array $headers)
     public function clearHeaders()
     {
         $this->headers = array(
-            'User-Agent' => sprintf('%s', $this->options['user_agent']),
+            'User-Agent' => \sprintf('%s', $this->options['user_agent']),
         );
     }
 
@@ -74,7 +74,7 @@ public function clearHeaders()
     /**
      * {@inheritDoc}
      */
-    public function get($path, array $parameters = array(), array $headers = array())
+    public function get($path, array $parameters = [], array $headers = [])
     {
         $path .= '?'. http_build_query($parameters);
         return $this->request($path, null, 'GET', $headers);
@@ -83,7 +83,7 @@ public function get($path, array $parameters = array(), array $headers = array()
     /**
      * {@inheritDoc}
      */
-    public function post($path, $body = null, array $headers = array())
+    public function post($path, $body = null, array $headers = [])
     {
         if (!isset($headers['Content-Type'])) {
             $headers['Content-Type'] = 'application/x-www-form-urlencoded';
@@ -95,7 +95,7 @@ public function post($path, $body = null, array $headers = array())
     /**
      * {@inheritDoc}
      */
-    public function patch($path, $body = null, array $headers = array())
+    public function patch($path, $body = null, array $headers = [])
     {
         if (!isset($headers['Content-Type'])) {
             $headers['Content-Type'] = 'application/x-www-form-urlencoded';
@@ -107,7 +107,7 @@ public function patch($path, $body = null, array $headers = array())
     /**
      * {@inheritDoc}
      */
-    public function delete($path, $body = null, array $headers = array())
+    public function delete($path, $body = null, array $headers = [])
     {
         return $this->request($path, $body, 'DELETE', $headers);
     }
@@ -115,7 +115,7 @@ public function delete($path, $body = null, array $headers = array())
     /**
      * {@inheritDoc}
      */
-    public function put($path, $body, array $headers = array())
+    public function put($path, $body, array $headers = [])
     {
         if (!isset($headers['Content-Type'])) {
             $headers['Content-Type'] = 'application/x-www-form-urlencoded';
@@ -130,8 +130,8 @@ public function request(
         $path,
         $body = null,
         $httpMethod = 'GET',
-        array $headers = array(),
-        array $options = array()
+        array $headers = [],
+        array $options = []
     ) {
         $request = $this->createRequest($httpMethod, $path, $body, $headers);
         try {
@@ -166,13 +166,13 @@ public function getLastResponse()
      * @param string $httpMethod
      * @param string $path
      *
-     * @return mixed|\Psr\Http\Message\ResponseInterface
+     * @return Request
      */
     protected function createRequest(
         $httpMethod,
         $path,
         $body = null,
-        array $headers = array()
+        array $headers = []
     ) {
         return new Request(
             $httpMethod,
diff --git a/src/Lamia/HttpClient/HttpClientInterface.php b/src/Lamia/HttpClient/HttpClientInterface.php
index 97cc18d..aab7f46 100644
--- a/src/Lamia/HttpClient/HttpClientInterface.php
+++ b/src/Lamia/HttpClient/HttpClientInterface.php
@@ -2,8 +2,11 @@
 
 namespace Lamia\HttpClient;
 
-use GuzzleHttp\Psr7\Response;
+use GuzzleHttp\Exception\GuzzleException;
+use Lamia\HttpClient\Exception\ErrorException;
 use Lamia\HttpClient\Exception\InvalidArgumentException;
+use Lamia\HttpClient\Exception\RuntimeException;
+use Psr\Http\Message\ResponseInterface;
 
 interface HttpClientInterface
 {
@@ -14,9 +17,9 @@ interface HttpClientInterface
      * @param array  $parameters GET Parameters
      * @param array  $headers    Reconfigure the request headers for this call only
      *
-     * @return Response
+     * @return ResponseInterface
      */
-    public function get($path, array $parameters = array(), array $headers = array());
+    public function get($path, array $parameters = [], array $headers = []);
     /**
      * Send a POST request
      *
@@ -24,9 +27,9 @@ public function get($path, array $parameters = array(), array $headers = array()
      * @param mixed  $body    Request body
      * @param array  $headers Reconfigure the request headers for this call only
      *
-     * @return Response
+     * @return ResponseInterface
      */
-    public function post($path, $body = null, array $headers = array());
+    public function post($path, $body = null, array $headers = []);
     /**
      * Send a PATCH request
      *
@@ -35,9 +38,9 @@ public function post($path, $body = null, array $headers = array());
      * @param array  $headers Reconfigure the request headers for this call only
      *
      * @internal param array $parameters Request body
-     * @return Response
+     * @return ResponseInterface
      */
-    public function patch($path, $body = null, array $headers = array());
+    public function patch($path, $body = null, array $headers = []);
     /**
      * Send a PUT request
      *
@@ -45,9 +48,9 @@ public function patch($path, $body = null, array $headers = array());
      * @param mixed  $body    Request body
      * @param array  $headers Reconfigure the request headers for this call only
      *
-     * @return Response
+     * @return ResponseInterface
      */
-    public function put($path, $body, array $headers = array());
+    public function put($path, $body, array $headers = []);
     /**
      * Send a DELETE request
      *
@@ -55,9 +58,9 @@ public function put($path, $body, array $headers = array());
      * @param mixed  $body    Request body
      * @param array  $headers Reconfigure the request headers for this call only
      *
-     * @return Response
+     * @return ResponseInterface
      */
-    public function delete($path, $body = null, array $headers = array());
+    public function delete($path, $body = null, array $headers = []);
     /**
      * Send a request to the server, receive a response,
      * decode the response and returns an associative array
@@ -67,23 +70,28 @@ public function delete($path, $body = null, array $headers = array());
      * @param string $httpMethod HTTP method to use
      * @param array  $headers    Request headers
      *
-     * @return Response
+     * @return ResponseInterface
+     *
+     * @throws ErrorException
+     * @throws RuntimeException
+     * @throws GuzzleException
      */
-    public function request($path, $body, $httpMethod = 'GET', array $headers = array());
+    public function request($path, $body, $httpMethod = 'GET', array $headers = []);
     /**
      * Change an option value.
      *
-     * @param string $name  The option name
-     * @param mixed  $value The value
+     * @param string $name The option name
+     * @param mixed $value The value
      *
      * @throws InvalidArgumentException
+     * 
      * @return void
      */
     public function setOption($name, $value);
     /**
      * Set HTTP headers
      *
-     * @param  array $headers
+     * @param array<string, string|int|float> $headers
      * @return void
      */
     public function setHeaders(array $headers);
diff --git a/tests/Lamia/HttpClient/HttpClientTest.php b/tests/Lamia/HttpClient/HttpClientTest.php
index 28cf124..ad2edb0 100644
--- a/tests/Lamia/HttpClient/HttpClientTest.php
+++ b/tests/Lamia/HttpClient/HttpClientTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace Lamia\HttpClient;
 
@@ -23,14 +24,14 @@ public function testDummyGetRequest()
     public function testDummyGetRequestWithParams()
     {
         $newInstance = new HttpClient(self::TEST_URL);
-        $result = json_decode($newInstance->get('posts', array('userId' => 2))->getBody()->getContents());
+        $result = json_decode($newInstance->get('posts', ['userId' => 2])->getBody()->getContents());
         $this->assertEquals(2, $result[1]->userId);
     }
 
     public function testDummyPostRequest()
     {
         $newInstance = new HttpClient(self::TEST_URL);
-        $result = json_decode($newInstance->post('posts', json_encode(array('title' => 'test', 'body' => 'blabla', 'userId' => 1)))->getBody()->getContents());
+        $result = json_decode($newInstance->post('posts', json_encode(['title' => 'test', 'body' => 'blabla', 'userId' => 1]))->getBody()->getContents());
 
         $this->assertNotEmpty($result->id);
     }
@@ -38,7 +39,7 @@ public function testDummyPostRequest()
     public function testDummyPutRequest()
     {
         $newInstance = new HttpClient(self::TEST_URL);
-        $result = json_decode($newInstance->put('posts/1', json_encode(array('id' => 1, 'title' => 'test', 'body' => 'blabla', 'userId' => 1)))->getBody()->getContents());
+        $result = json_decode($newInstance->put('posts/1', json_encode(['id' => 1, 'title' => 'test', 'body' => 'blabla', 'userId' => 1]))->getBody()->getContents());
 
         $this->assertEquals(1, $result->id);
     }
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
deleted file mode 100644
index ec0a61f..0000000
--- a/tests/bootstrap.php
+++ /dev/null
@@ -1,21 +0,0 @@
-<?php
-
-ini_set('display_errors', 1);
-error_reporting(-1);
-
-function includeIfExists($file)
-{
-    if (file_exists($file)) {
-        return include $file;
-    }
-}
-
-if ((!$loader = includeIfExists(__DIR__.'/../vendor/autoload.php')) && (!$loader = includeIfExists(__DIR__.'/../../../.composer/autoload.php'))) {
-    die('You must set up the project dependencies, run the following commands:'.PHP_EOL.
-        'curl -s http://getcomposer.org/installer | php'.PHP_EOL.
-        'php composer.phar install'.PHP_EOL);
-}
-
-$loader->add('Lamia\HttpClient', __DIR__);
-
-return $loader;