diff --git a/fhem/FHEM/73_WaterCalculator.pm b/fhem/FHEM/73_WaterCalculator.pm
index e49bf2935..477c135b7 100644
--- a/fhem/FHEM/73_WaterCalculator.pm
+++ b/fhem/FHEM/73_WaterCalculator.pm
@@ -52,6 +52,7 @@
 package main;
 use strict;
 use warnings;
+use Time::Local;
 use FHEM::Meta;
 
 ###START###### Initialize module ##############################################################################START####