diff --git a/tests/Mailgun/Tests/Mock/Connection/TestBroker.php b/tests/Mailgun/Tests/Mock/Connection/TestBroker.php
index 6652aa5..b1dee7e 100644
--- a/tests/Mailgun/Tests/Mock/Connection/TestBroker.php
+++ b/tests/Mailgun/Tests/Mock/Connection/TestBroker.php
@@ -19,7 +19,7 @@ class TestBroker extends RestClient
         $this->apiEndpoint = $apiHost;
     }
 
-    public function post($endpointUrl, $postData = array(), $files = array())
+    public function post($endpointUrl, array $postData = array(), $files = array())
     {
         return $this->testResponseHandler($endpointUrl, $httpResponseCode = 200);
     }