diff --git a/modules/default/calendar/calendarutils.js b/modules/default/calendar/calendarutils.js
index 9d9876e1..91679f13 100644
--- a/modules/default/calendar/calendarutils.js
+++ b/modules/default/calendar/calendarutils.js
@@ -307,10 +307,10 @@ const CalendarUtils = {
 					// Loop through the set of date entries to see which recurrences should be added to our event list.
 					for (let d in dates) {
 						let date = dates[d];
-						// FIXME: We now use node-ical instead of ical.js, but method stays the same.
-						// ical.js started returning recurrences and exdates as ISOStrings without time information.
-						// .toISOString().substring(0,10) is the method they use to calculate keys, so we'll do the same
-						// (see https://github.com/peterbraden/ical.js/pull/84 )
+						// Remove the time information of each date by using its substring, using the following method:
+						// .toISOString().substring(0,10).
+						// since the date is given as ISOString with YYYY-MM-DDTHH:MM:SS.SSSZ
+						// (see https://momentjs.com/docs/#/displaying/as-iso-string/).
 						const dateKey = date.toISOString().substring(0, 10);
 						let curEvent = event;
 						let showRecurrence = true;