diff --git a/fhem/FHEM/57_Calendar.pm b/fhem/FHEM/57_Calendar.pm
index 45c7c7c59..860365c80 100644
--- a/fhem/FHEM/57_Calendar.pm
+++ b/fhem/FHEM/57_Calendar.pm
@@ -14,6 +14,7 @@
 
 use strict;
 use warnings;
+use HttpUtils.pm;
 
 
 ##############################################