diff --git a/osu.Game/Online/Multiplayer/MatchRulesetRoomState.cs b/osu.Game/Online/Multiplayer/MatchRulesetRoomState.cs
index be8e54d341..773c9a55e8 100644
--- a/osu.Game/Online/Multiplayer/MatchRulesetRoomState.cs
+++ b/osu.Game/Online/Multiplayer/MatchRulesetRoomState.cs
@@ -3,6 +3,7 @@
 
 using System;
 using MessagePack;
+using osu.Game.Online.Multiplayer.MatchRulesets.TeamVs;
 
 #nullable enable
 
@@ -14,7 +15,8 @@ namespace osu.Game.Online.Multiplayer
     /// </summary>
     [Serializable]
     [MessagePackObject]
-    public class MatchRulesetRoomState
+    [Union(0, typeof(TeamVsMatchRoomState))]
+    public abstract class MatchRulesetRoomState
     {
     }
 }
diff --git a/osu.Game/Online/Multiplayer/MatchRulesetUserState.cs b/osu.Game/Online/Multiplayer/MatchRulesetUserState.cs
index 6fa0024c3d..36eae2447e 100644
--- a/osu.Game/Online/Multiplayer/MatchRulesetUserState.cs
+++ b/osu.Game/Online/Multiplayer/MatchRulesetUserState.cs
@@ -3,6 +3,7 @@
 
 using System;
 using MessagePack;
+using osu.Game.Online.Multiplayer.MatchRulesets.TeamVs;
 
 #nullable enable
 
@@ -14,7 +15,8 @@ namespace osu.Game.Online.Multiplayer
     /// </summary>
     [Serializable]
     [MessagePackObject]
-    public class MatchRulesetUserState
+    [Union(0, typeof(TeamVsMatchUserState))]
+    public abstract class MatchRulesetUserState
     {
     }
 }
diff --git a/osu.Game/Online/Multiplayer/MatchRulesets/TeamVs/TeamVsMatchRoomState.cs b/osu.Game/Online/Multiplayer/MatchRulesets/TeamVs/TeamVsMatchRoomState.cs
index 57aae6e534..338b9c965d 100644
--- a/osu.Game/Online/Multiplayer/MatchRulesets/TeamVs/TeamVsMatchRoomState.cs
+++ b/osu.Game/Online/Multiplayer/MatchRulesets/TeamVs/TeamVsMatchRoomState.cs
@@ -8,6 +8,7 @@ using MessagePack;
 
 namespace osu.Game.Online.Multiplayer.MatchRulesets.TeamVs
 {
+    [MessagePackObject]
     public class TeamVsMatchRoomState : MatchRulesetRoomState
     {
         [Key(0)]