diff --git a/fhem/FHEM/73_WaterCalculator.pm b/fhem/FHEM/73_WaterCalculator.pm
index 0323c1060..69c3c3b67 100644
--- a/fhem/FHEM/73_WaterCalculator.pm
+++ b/fhem/FHEM/73_WaterCalculator.pm
@@ -54,6 +54,7 @@ use strict;
 use warnings;
 use Time::Local;
 use FHEM::Meta;
+use Data::Dumper;
 my %WaterCalculator_gets;
 my %WaterCalculator_sets;