diff --git a/fhem/FHEM/57_CalDav.pm b/fhem/FHEM/57_CalDav.pm
index c69c4faec..8b74ae419 100644
--- a/fhem/FHEM/57_CalDav.pm
+++ b/fhem/FHEM/57_CalDav.pm
@@ -47,7 +47,7 @@ sub CalDav_Process($$$) {
   my $url     = $hash->{URL};
   my $options = $hash->{OPTIONS};
   
-  unless $data {
+  unless ($data) {
     Log3 $hash,1,"CalDav: Maybe this is the wrong way to use your calendar. Try 57_Calendar.pm instead.";
     return;
   }