diff --git a/views.api.php b/views.api.php
index 1e2b9db..8a656a5 100644
--- a/views.api.php
+++ b/views.api.php
@@ -469,6 +469,9 @@ function hook_views_data() {
  * returned by MODULENAME_views_api(), or the same directory as the .module
  * file, if 'path' is unspecified.
  *
+ * @param $data
+ *   An array of all views data, @see hook_views_data().
+ *
  * @see hook_views_data().
  */
 function hook_views_data_alter(&$data) {