diff --git a/fhem/contrib/00_TAHR.pm b/fhem/contrib/00_TAHR.pm
index 4b460078e..7706c256b 100644
--- a/fhem/contrib/00_TAHR.pm
+++ b/fhem/contrib/00_TAHR.pm
@@ -136,6 +136,7 @@ TAHR_Poll($)
   # FIXME
   DevIo_SimpleWrite($hash, "02"); # Request data
   InternalTimer(gettimeofday()+5, "TAHR_Poll", $hash, 0);
+  return undef;
 }
 
 sub