diff --git a/src/Http/Client.php b/src/Http/Client.php
index 0248917..c89be40 100644
--- a/src/Http/Client.php
+++ b/src/Http/Client.php
@@ -30,7 +30,7 @@ class Client implements ClientInterface
     /**
     * @var string
     */
-    private $apiVersion = '4.1.0';
+    private $apiVersion = '4.2.0';
 
     /**
     * @var string
diff --git a/tests/Unit/Http/ClientTest.php b/tests/Unit/Http/ClientTest.php
index 48d96ee..559d5bc 100644
--- a/tests/Unit/Http/ClientTest.php
+++ b/tests/Unit/Http/ClientTest.php
@@ -35,7 +35,7 @@ public function testGetUserAgent()
             ->setMethods(null)
             ->getMock();
 
-        $this->assertEquals("chartmogul-php/4.1.0/PHP-".PHP_MAJOR_VERSION.".".PHP_MINOR_VERSION, $mock->getUserAgent());
+        $this->assertEquals("chartmogul-php/4.2.0/PHP-".PHP_MAJOR_VERSION.".".PHP_MINOR_VERSION, $mock->getUserAgent());
     }
 
     public function testGetBasicAuthHeader()