diff --git a/src/Adapter/Guzzle.php b/src/Adapter/Guzzle.php
index 874f3fe..c9ac7cf 100644
--- a/src/Adapter/Guzzle.php
+++ b/src/Adapter/Guzzle.php
@@ -50,7 +50,7 @@ class Guzzle implements Adapter
     {
         $response = $this->client->post($uri, [
                 'headers' => $headers,
-                'form_params' => $body
+                'json' => $body
             ]
         );
 
@@ -125,4 +125,4 @@ class Guzzle implements Adapter
             throw new ResponseException("Request was unsuccessful.");
         }
     }
-}
\ No newline at end of file
+}
diff --git a/tests/Adapter/GuzzleTest.php b/tests/Adapter/GuzzleTest.php
index 5049215..3d1e27a 100644
--- a/tests/Adapter/GuzzleTest.php
+++ b/tests/Adapter/GuzzleTest.php
@@ -47,7 +47,7 @@ class GuzzleTest extends PHPUnit_Framework_TestCase
         $this->assertEquals("application/json", $headers["Content-Type"][0]);
 
         $body = json_decode($response->getBody());
-        $this->assertEquals("Testing a POST request.", $body->form->{"X-Post-Test"});
+        $this->assertEquals("Testing a POST request.", $body->json->{"X-Post-Test"});
     }
 
     public function testPut()