diff --git a/commerce_dunning.module b/commerce_dunning.module
index aaf1568..99a646c 100644
--- a/commerce_dunning.module
+++ b/commerce_dunning.module
@@ -33,6 +33,12 @@ function commerce_dunning_commerce_order_status_info() {
  * Short action description can also contain a variable, for example the number
  * of days after a certain action should be evaluated in the dunning process.
  * E.g.: dunning-22-charge-attempt-2-days
+ *
+ * @param int $order_id
+ *   Order ID.
+ *
+ * @return array
+ *   Array keyed by task tid's.
  */
 function commerce_dunning_get_scheduled_tasks($order_id = NULL) {
   $return = array();