diff --git a/DMAPI/server_tools.dm b/DMAPI/server_tools.dm
index ea1172964d..9ff5b4ee28 100644
--- a/DMAPI/server_tools.dm
+++ b/DMAPI/server_tools.dm
@@ -98,6 +98,8 @@
 #define SERVICE_REQUEST_WORLD_REBOOT "worldreboot"
 #define SERVICE_REQUEST_API_VERSION "api_ver"
 
+#define SERVICE_RETURN_SUCCESS "SUCCESS"
+
 /*
 The MIT License
 
diff --git a/DMAPI/st_interface.dm b/DMAPI/st_interface.dm
index 727e7d3c8f..4bf3db1775 100644
--- a/DMAPI/st_interface.dm
+++ b/DMAPI/st_interface.dm
@@ -72,7 +72,7 @@ SERVER_TOOLS_DEFINE_AND_SET_GLOBAL(server_tools_api_compatible, FALSE)
 	switch(command)
 		if(SERVICE_CMD_API_COMPATIBLE)
 			SERVER_TOOLS_WRITE_GLOBAL(server_tools_api_compatible, TRUE)
-			return "SUCCESS"
+			return SERVICE_RETURN_SUCCESS
 		if(SERVICE_CMD_HARD_REBOOT)
 			if(SERVER_TOOLS_READ_GLOBAL(reboot_mode) != REBOOT_MODE_HARD)
 				SERVER_TOOLS_WRITE_GLOBAL(reboot_mode, REBOOT_MODE_HARD)
@@ -88,7 +88,7 @@ SERVER_TOOLS_DEFINE_AND_SET_GLOBAL(server_tools_api_compatible, FALSE)
 			if(!istext(msg) || !msg)
 				return "No message set!"
 			SERVER_TOOLS_WORLD_ANNOUNCE(msg)
-			return "SUCCESS"
+			return SERVICE_RETURN_SUCCESS
 		if(SERVICE_CMD_PLAYER_COUNT)
 			return "[SERVER_TOOLS_CLIENT_COUNT]"
 		if(SERVICE_CMD_LIST_CUSTOM)
@@ -96,7 +96,7 @@ SERVER_TOOLS_DEFINE_AND_SET_GLOBAL(server_tools_api_compatible, FALSE)
 		else
 			var/custom_command_result = HandleServiceCustomCommand(lowertext(command), params[SERVICE_CMD_PARAM_SENDER], params[SERVICE_CMD_PARAM_CUSTOM])
 			if(custom_command_result)
-				return istext(custom_command_result) ? custom_command_result : "SUCCESS"
+				return istext(custom_command_result) ? custom_command_result : SERVICE_RETURN_SUCCESS
 			return "Unknown command: [command]"
 
 /*
diff --git a/TGServerService/ServerInstance/DreamDaemon.cs b/TGServerService/ServerInstance/DreamDaemon.cs
index 9f68a48bb1..30145c5051 100644
--- a/TGServerService/ServerInstance/DreamDaemon.cs
+++ b/TGServerService/ServerInstance/DreamDaemon.cs
@@ -577,7 +577,7 @@ namespace TGServerService
 
 					GenCommsKey();
 					StartingSecurity = Config.Security;
-					Proc.StartInfo.Arguments = String.Format("{0} -port {1} {5}-close -verbose -params \"server_service={3}&server_service_version={4}&server_instance={6}\" -{2} -public", DMB, Config.Port, SecurityWord(), serviceCommsKey, Version(), Config.Webclient ? "-webclient " : "", Config.Name);
+					Proc.StartInfo.Arguments = String.Format("{0} -port {1} {5}-close -verbose -params \"server_service={3}&server_service_version={4}&{6}={7}\" -{2} -public", DMB, Config.Port, SecurityWord(), serviceCommsKey, Version(), Config.Webclient ? "-webclient " : "", SPInstanceName, Config.Name);
 					UpdateInterfaceDll(true);
 					lock (topicLock)
 					{
diff --git a/TGServerService/ServerInstance/Interop.cs b/TGServerService/ServerInstance/Interop.cs
index 6ebf909035..e796527fec 100644
--- a/TGServerService/ServerInstance/Interop.cs
+++ b/TGServerService/ServerInstance/Interop.cs
@@ -24,13 +24,20 @@ namespace TGServerService
 		const int AllowedMajorAPIVersion = 1;
 		Version GameAPIVersion;
 
+		const string SPInstanceName = "server_instance";
+
 		//See code/modules/server_tools/server_tools.dm for command switch
 		const string SCHardReboot = "hard_reboot";  //requests that dreamdaemon restarts when the round ends
 		const string SCGracefulShutdown = "graceful_shutdown";  //requests that dreamdaemon stops when the round ends
 		const string SCWorldAnnounce = "world_announce";	//sends param 'message' to the world
 		const string SCListCustomCommands = "list_custom_commands"; //Get a list of commands supported by the server
 		const string SCAPICompat = "api_compat";    //Tells the server we understand each other
-		const string SCPlayerCount = "client_count";	//Gets the number of connected clients
+		const string SCPlayerCount = "client_count";    //Gets the number of connected client
+
+		/// <summary>
+		/// String returned when a command completes successfully with no output
+		/// </summary>
+		const string SRetSuccess = "SUCCESS";
 
 		const string SRKillProcess = "killme";
 		const string SRIRCBroadcast = "irc";
diff --git a/TGServerService/Service.cs b/TGServerService/Service.cs
index 6ca622bae0..6c6f0c897d 100644
--- a/TGServerService/Service.cs
+++ b/TGServerService/Service.cs
@@ -63,6 +63,20 @@ namespace TGServerService
 			Run(ActiveService);
 		}
 
+		/// <summary>
+		/// Checks an <paramref name="instanceName"/> for illegal characters
+		/// </summary>
+		/// <param name="instanceName">The <see cref="ServerInstance"/> name to check</param>
+		/// <returns><see langword="null"/> if <paramref name="instanceName"/> contains no illegal characters, error message otherwise</returns>
+		static string CheckInstanceName(string instanceName)
+		{
+			char[] bannedCharacters = { ';', '&', '=', '%' };
+			foreach (var I in bannedCharacters)
+				if (instanceName.Contains(I.ToString()))
+					return "Instance names may not contain the following characters: ';', '&', '=', or '%'";
+			return null;
+		}
+
 		/// <summary>
 		/// Sets up the service name. Do not add any more code due to the reasons outlined in <see cref="Launch"/>
 		/// </summary>
@@ -401,6 +415,9 @@ namespace TGServerService
 		/// <inheritdoc />
 		public string CreateInstance(string Name, string path)
 		{
+			var res = CheckInstanceName(Name);
+			if (res != null)
+				return res;
 			if (File.Exists(path) || Directory.Exists(path))
 				return "Cannot create instance at pre-existing path!";
 			var Config = Properties.Settings.Default;
@@ -542,6 +559,9 @@ namespace TGServerService
 		{
 			if (name == new_name)
 				return null;
+			var res = CheckInstanceName(new_name);
+			if (res != null)
+				return res;
 			lock (this)
 			{
 				//we have to check em all anyway