diff --git a/fhem/FHEM/98_configdb.pm b/fhem/FHEM/98_configdb.pm
index 86f2a3de6..84be65e45 100644
--- a/fhem/FHEM/98_configdb.pm
+++ b/fhem/FHEM/98_configdb.pm
@@ -49,7 +49,7 @@ sub CommandConfigdb($$) {
 				}
 			} elsif($param2 eq "") {
 			# delete attribute
-				undef($configDB{attr}{$param1});
+				delete $configDB{attr}{$param1};
 				$ret = " attribute $param1 deleted";
 			} else {
 			# set attribute
@@ -218,8 +218,10 @@ sub CommandConfigdb($$) {
 		}
 
 		when ('list') {
-			$param1 = $param1 ? $param1 : '%';
-			$param2 = $param2 ? $param2 : 0;
+			$param1 //= '%';
+			$param2 //= 0;
+			$ret = "list not allowed for configDB itself.";
+			break if($param1 =~ m/configdb/i);
 			Log3('configdb', 4, "configdb: list requested for device: $param1 in version $param2.");
 			$ret = _cfgDB_Search($param1,$param2,1);
 		}