diff --git a/utils/client-schedule.ts b/utils/client-schedule.ts
index 1e64a19..90ac0ba 100644
--- a/utils/client-schedule.ts
+++ b/utils/client-schedule.ts
@@ -191,7 +191,7 @@ export class ClientScheduleEvent extends ClientEntity<ApiScheduleEvent> {
 		for (const id of this.serverSlotIds) {
 			this.schedule.eventSlots.get(id)!.discard();
 		}
-		for (const id of this.slotIds.difference(this.serverSlotIds)) {
+		for (const id of toRaw(this.slotIds).difference(this.serverSlotIds)) {
 			const slot = this.schedule.eventSlots.get(id)!;
 			slot.setEventId(slot.serverEventId);
 		}
@@ -563,7 +563,7 @@ export class ClientScheduleShift extends ClientEntity<ApiScheduleShift> {
 		for (const id of this.serverSlotIds) {
 			this.schedule.shiftSlots.get(id)!.discard();
 		}
-		for (const id of this.slotIds.difference(this.serverSlotIds)) {
+		for (const id of toRaw(this.slotIds).difference(this.serverSlotIds)) {
 			const slot = this.schedule.shiftSlots.get(id)!;
 			slot.setShiftId(slot.serverShiftId);
 		}