diff --git includes/form.inc includes/form.inc
index 3d69b44..cf73877 100644
--- includes/form.inc
+++ includes/form.inc
@@ -2624,6 +2624,7 @@ function form_get_options($element, $key) {
  *   - element: An associative array containing the properties of the element.
  *     Properties used: #attributes, #children, #collapsed, #collapsible,
  *     #description, #id, #title, #value.
+ *     Required properties:  #attributes (must be an Array), #children (must be a String).
  *
  * @ingroup themeable
  */