diff --git a/src/wp-includes/default-constants.php b/src/wp-includes/default-constants.php
index eb86853fe0..12d6123023 100644
--- a/src/wp-includes/default-constants.php
+++ b/src/wp-includes/default-constants.php
@@ -101,6 +101,7 @@ function wp_initial_constants() {
 	 * If you need more accuracy please consider using the DateTime class (http://php.net/manual/class.datetime.php).
 	 *
 	 * @since 3.5.0
+	 * @since 4.4.0 Introduced `MONTH_IN_SECONDS`.
 	 */
 	define( 'MINUTE_IN_SECONDS', 60 );
 	define( 'HOUR_IN_SECONDS',   60 * MINUTE_IN_SECONDS );