diff --git a/DnsServerCore/Dhcp/Options/ClientFullyQualifiedDomainNameOption.cs b/DnsServerCore/Dhcp/Options/ClientFullyQualifiedDomainNameOption.cs
index 05e33760..6ebac111 100644
--- a/DnsServerCore/Dhcp/Options/ClientFullyQualifiedDomainNameOption.cs
+++ b/DnsServerCore/Dhcp/Options/ClientFullyQualifiedDomainNameOption.cs
@@ -1,6 +1,6 @@
 /*
 Technitium DNS Server
-Copyright (C) 2019  Shreyas Zare (shreyas@technitium.com)
+Copyright (C) 2021  Shreyas Zare (shreyas@technitium.com)
 
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -17,6 +17,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 */
 
+using System;
 using System.IO;
 using System.Text;
 using TechnitiumLibrary.IO;
@@ -24,6 +25,7 @@ using TechnitiumLibrary.Net.Dns;
 
 namespace DnsServerCore.Dhcp.Options
 {
+    [Flags]
     enum ClientFullyQualifiedDomainNameFlags : byte
     {
         None = 0,