diff --git a/fhem/FHEM/32_TechemHKV.pm b/fhem/FHEM/32_TechemHKV.pm
index 5c62c74b2..d0208af04 100644
--- a/fhem/FHEM/32_TechemHKV.pm
+++ b/fhem/FHEM/32_TechemHKV.pm
@@ -187,7 +187,7 @@ TechemHKV_Parse(@) {
   }
   # broadcast
 
-  return (undef);
+  return ('');
 }
 
 sub