diff --git a/FHEM/00_MQTT2_SERVER.pm b/FHEM/00_MQTT2_SERVER.pm
index 8b101b990..4fe48b9c4 100644
--- a/FHEM/00_MQTT2_SERVER.pm
+++ b/FHEM/00_MQTT2_SERVER.pm
@@ -236,7 +236,7 @@ MQTT2_SERVER_Set($@)
     my $rname = AttrVal($hash->{NAME}, "hideRetain", 0) ? "RETAIN" : ".RETAIN";
     delete($hash->{READINGS}{$rname});
     delete($hash->{retain});
-
+    return undef;
   }
 }