diff --git a/backend/service/ical/icalFileGeneration.go b/backend/service/ical/icalFileGeneration.go
index e4b3134..f39e618 100644
--- a/backend/service/ical/icalFileGeneration.go
+++ b/backend/service/ical/icalFileGeneration.go
@@ -41,7 +41,7 @@ func (icalModel IcalModel) EmitICal() goics.Componenter {
 		s.AddProperty(goics.FormatDateTime("DTSTAMP", time.Now().Local().In(europeTime)))
 
 		// create a unique id for the event by hashing the event start, end, course and name
-		var eventHash = functions.HashString(event.Start.String() + event.End.String() + event.Course + event.Name)
+		var eventHash = functions.HashString(event.Start.String() + event.End.String() + event.Course + event.Name + event.Rooms)
 
 		s.AddProperty("UID", eventHash+"@htwkalender.de")
 		s.AddProperty(goics.FormatDateTime("DTEND", event.End.Time().Local().In(europeTime)))