diff --git a/src/mtime_t_event.inc b/src/mtime_t_event.inc
index 2b78e4636c5af5464ff42c0063a70821d32ae28f..b36a406ae293b6ea1f8c53d0d481808b7e308b3a 100644
--- a/src/mtime_t_event.inc
+++ b/src/mtime_t_event.inc
@@ -308,6 +308,7 @@
     ELSE
       allocate(this%last_event_in_group%nextEventInGroup, source=event_to_add)
       this%last_event_in_group => this%last_event_in_group%nextEventInGroup
+      NULLIFY(this%last_event_in_group%nextEventInGroup)
     ENDIF
   END SUBROUTINE t_eventGroup_addToGroup