diff --git a/OpenRA.Mods.Common/ServerTraits/LobbyCommands.cs b/OpenRA.Mods.Common/ServerTraits/LobbyCommands.cs
index e1366b8139..42810149e7 100644
--- a/OpenRA.Mods.Common/ServerTraits/LobbyCommands.cs
+++ b/OpenRA.Mods.Common/ServerTraits/LobbyCommands.cs
@@ -729,6 +729,12 @@ namespace OpenRA.Mods.Common.Server
 				if (oo.Value == split[1])
 					return true;
 
+				if (!option.Values.ContainsKey(split[1]))
+				{
+					server.SendLocalizedMessageTo(conn, InvalidConfigurationCommand);
+					return true;
+				}
+
 				oo.Value = oo.PreferredValue = split[1];
 
 				server.SyncLobbyGlobalSettings();
diff --git a/OpenRA.Mods.Common/ServerTraits/SkirmishLogic.cs b/OpenRA.Mods.Common/ServerTraits/SkirmishLogic.cs
index 99e02d3e8a..537ef429bd 100644
--- a/OpenRA.Mods.Common/ServerTraits/SkirmishLogic.cs
+++ b/OpenRA.Mods.Common/ServerTraits/SkirmishLogic.cs
@@ -84,7 +84,7 @@ namespace OpenRA.Mods.Common.Server
 
 				foreach (var optionNode in optionsNode.Value.Nodes)
 				{
-					if (options.TryGetValue(optionNode.Key, out var option) && !option.IsLocked)
+					if (options.TryGetValue(optionNode.Key, out var option) && !option.IsLocked && option.Values.ContainsKey(optionNode.Value.Value))
 					{
 						var oo = server.LobbyInfo.GlobalSettings.LobbyOptions[option.Id];
 						oo.Value = oo.PreferredValue = optionNode.Value.Value;