diff --git a/tests/authorization/AuthServerTest.php b/tests/authorization/AuthServerTest.php
index 50b03147..88f928b5 100644
--- a/tests/authorization/AuthServerTest.php
+++ b/tests/authorization/AuthServerTest.php
@@ -210,6 +210,16 @@ class Authorization_Server_test extends PHPUnit_Framework_TestCase
         $this->assertTrue($result instanceof OAuth2\Grant\GrantTypeInterface);
     }
 
+    /**
+     * @expectedException        OAuth2\Exception\InvalidGrantTypeException
+     * @expectedExceptionCode    9
+     */
+    public function test_getGrantType_fail()
+    {
+        $a = $this->returnDefault();
+        $a->getGrantType('blah');
+    }
+
     /**
      * @expectedException        OAuth2\Exception\ClientException
      * @expectedExceptionCode    0