diff --git a/composer.json b/composer.json
index 734ef64..7f7a0b0 100644
--- a/composer.json
+++ b/composer.json
@@ -28,9 +28,10 @@
   "require": {
     "php": ">=5.4.0",
     "yiisoft/yii2": "~2.0.4",
-    "mailgun/mailgun-php": "*",
+    "mailgun/mailgun-php": "^2.0",
     "yiisoft/yii2-twig": "~2.0.3",
-    "trntv/yii2-aceeditor": "*",
+    "trntv/yii2-aceeditor": "~2.0",
+    "php-http/guzzle6-adapter": "~1.0",
     "baibaratsky/yii2-serialized-attributes-behavior": "~1.1"
   },
   "suggest": {
diff --git a/src/transports/MailGun.php b/src/transports/MailGun.php
index d561ab7..242fbcd 100644
--- a/src/transports/MailGun.php
+++ b/src/transports/MailGun.php
@@ -6,6 +6,7 @@
 
 namespace yarcode\email\transports;
 
+use Http\Adapter\Guzzle6\Client;
 use yarcode\email\interfaces\TransportInterface;
 use yii\base\Component;
 use yii\helpers\VarDumper;
@@ -27,7 +28,9 @@ public function init()
         assert(isset($this->domain));
 
         parent::init();
-        $this->_api = new \Mailgun\Mailgun($this->apiKey);
+
+        $client = new Client();
+        $this->_api = new \Mailgun\Mailgun($this->apiKey, $client);
     }
 
     /**