diff --git a/gtk/gtktreestore.c b/gtk/gtktreestore.c
index 1ef7a3989c..a6e47af398 100644
--- a/gtk/gtktreestore.c
+++ b/gtk/gtktreestore.c
@@ -2248,8 +2248,8 @@ gtk_tree_store_reorder_func (gconstpointer a,
 
 /**
  * gtk_tree_store_reorder: (skip)
- * @tree_store: A #GtkTreeStore.
- * @parent: A #GtkTreeIter.
+ * @tree_store: A #GtkTreeStore
+ * @parent: A #GtkTreeIter, or %NULL
  * @new_order: (array): an array of integers mapping the new position of each child
  *      to its old position before the re-ordering,
  *      i.e. @new_order`[newpos] = oldpos`.