diff --git a/www/manager6/panel/IPSet.js b/www/manager6/panel/IPSet.js
index c449cdaa..d42d062d 100644
--- a/www/manager6/panel/IPSet.js
+++ b/www/manager6/panel/IPSet.js
@@ -203,6 +203,7 @@ Ext.define('PVE.IPSetCidrEdit', {
 		editable: true,
 		base_url: me.list_refs_url,
 		value: '',
+		allowBlank: false,
 		fieldLabel: gettext('IP/CIDR'),
 	    });
 	} else {