diff --git a/libraries/networking/src/udt/PacketHeaders.h b/libraries/networking/src/udt/PacketHeaders.h
index 6e1aca83e5..3c47cdcf09 100644
--- a/libraries/networking/src/udt/PacketHeaders.h
+++ b/libraries/networking/src/udt/PacketHeaders.h
@@ -313,7 +313,8 @@ enum class DomainListVersion : PacketVersion {
     PrePermissionsGrid = 18,
     PermissionsGrid,
     GetUsernameFromUUIDSupport,
-    GetMachineFingerprintFromUUIDSupport
+    GetMachineFingerprintFromUUIDSupport,
+    AuthenticationOptional
 };
 
 enum class AudioVersion : PacketVersion {