diff --git a/wp-includes/cron.php b/wp-includes/cron.php
index 7258cb0ce..c8261d8da 100644
--- a/wp-includes/cron.php
+++ b/wp-includes/cron.php
@@ -50,6 +50,8 @@ function wp_schedule_single_event( $timestamp, $hook, $args = array()) {
  * Valid values for the recurrence are hourly, daily and twicedaily.  These can
  * be extended using the cron_schedules filter in wp_get_schedules().
  *
+ * Use wp_next_scheduled() to prevent duplicates
+ *
  * @since 2.1.0
  *
  * @param int $timestamp Timestamp for when to run the event.
@@ -402,4 +404,4 @@ function _upgrade_cron_array($cron) {
 	$new_cron['version'] = 2;
 	update_option( 'cron', $new_cron );
 	return $new_cron;
-}
\ No newline at end of file
+}