diff --git a/application/libraries/REST_Controller.php b/application/libraries/REST_Controller.php
index 7d7c8a8a..cd9ae4bb 100755
--- a/application/libraries/REST_Controller.php
+++ b/application/libraries/REST_Controller.php
@@ -1281,7 +1281,7 @@ protected function _perform_library_auth($username = '', $password = null)
             $this->load->library($auth_library_class);
         }
 
-        return $auth_library_class->$auth_library_function($username, $password);
+        return $this->{$auth_library_class}->$auth_library_function($username, $password);
     }
 
     /**