diff --git a/src/main/java/org/olat/commons/calendar/CalendarUtils.java b/src/main/java/org/olat/commons/calendar/CalendarUtils.java
index 88d2c45ccc58c29275c83ac2a5430ab4a2a9c32c..4ba4ceb9d4241bb5b8fe5086a59159e2ef6db3b1 100644
--- a/src/main/java/org/olat/commons/calendar/CalendarUtils.java
+++ b/src/main/java/org/olat/commons/calendar/CalendarUtils.java
@@ -265,7 +265,9 @@ public class CalendarUtils {
 			for ( KalendarRecurEvent recurEvent : lstEvnt ) {
 				periodEvents.add(recurEvent);
 			}
-			if (event.getEnd().before(periodStart) || event.getBegin().after(periodEnd)) continue;
+			if ((event.getEnd() != null && event.getEnd().before(periodStart)) || event.getBegin().after(periodEnd)) {
+				continue;
+			}
 			periodEvents.add(event);
 		}
 		return periodEvents;
diff --git a/src/test/java/org/olat/commons/calendar/ICalFileCalendarManagerTest.java b/src/test/java/org/olat/commons/calendar/ICalFileCalendarManagerTest.java
index 0cd0c3f29297c09b3466a171d9183f9a2fdea279..53f4ddba35dcbaf81cd075ee71fbe1dc251bd254 100644
--- a/src/test/java/org/olat/commons/calendar/ICalFileCalendarManagerTest.java
+++ b/src/test/java/org/olat/commons/calendar/ICalFileCalendarManagerTest.java
@@ -123,6 +123,11 @@ public class ICalFileCalendarManagerTest extends OlatTestCase {
 		
 		//persist
 		calManager.persistCalendar(reloadCalWrapper.getKalendar());
+		
+		//an other possible RS
+		Date periodStart = new Date();
+		Date periodEnd = new Date();
+		CalendarUtils.listEventsForPeriod(reloadCalWrapper.getKalendar(), periodStart, periodEnd);
 	}
 	
 	/**