diff --git a/src/model/schedule.ts b/src/model/schedule.ts
index 7e4d06b..f100db0 100644
--- a/src/model/schedule.ts
+++ b/src/model/schedule.ts
@@ -130,8 +130,8 @@ export class ScheduleModel {
 					seriesId: series.id,
 					resourceId,
 					title: eventTitle,
-					startAt: eventStart,
-					endAt: eventEnd,
+					startAt: eventStart.toISOString(),
+					endAt: eventEnd.toISOString(),
 					isRecurring: !!series.recurrence_rule,
 					isException: !!exception,
 					status: "confirmed",