diff --git a/FHEM/57_Calendar.pm b/FHEM/57_Calendar.pm
index b61afd12e..99f10627b 100644
--- a/FHEM/57_Calendar.pm
+++ b/FHEM/57_Calendar.pm
@@ -658,6 +658,8 @@ sub clear($) {
 
 package ICal::Entry;
 
+sub getNextMonthlyDateByDay($$$);
+
 sub new($$) {
   my $class= shift;
   my ($type)= @_;