diff --git a/fhem/FHEM/90_at.pm b/fhem/FHEM/90_at.pm
index 612dd6a32..e283157a8 100755
--- a/fhem/FHEM/90_at.pm
+++ b/fhem/FHEM/90_at.pm
@@ -82,6 +82,7 @@ at_Define($$)
   $rel = "" if(!defined($rel));
   $rep = "" if(!defined($rep));
   $cnt = "" if(!defined($cnt));
+  delete $hash->{VOLATILE} if (defined($hash->{VOLATILE}));
   $hash->{RELATIVE} = ($rel ? "yes" : "no");
   $hash->{PERIODIC} = ($rep ? "yes" : "no");
   $hash->{TIMESPEC} = $tspec;