diff --git a/src/m_menu.c b/src/m_menu.c
index 6c93da048..e345a6a87 100644
--- a/src/m_menu.c
+++ b/src/m_menu.c
@@ -11371,7 +11371,7 @@ static void M_Refresh(INT32 choice)
 
 	// note: this is the one case where 0 is a valid room number
 	// because it corresponds to "All"
-	CL_UpdateServerList(!(ms_RoomId < 0), ms_RoomId);
+	CL_UpdateServerList(cv_masterserver_room_id.value >= 0, cv_masterserver_room_id.value);
 
 	// first page of servers
 	serverlistpage = 0;
@@ -11457,7 +11457,7 @@ static void M_DrawConnectMenu(void)
 		numPages = 1;
 
 	// Room name
-	if (ms_RoomId < 0)
+	if (cv_masterserver_room_id.value < 0)
 		V_DrawRightAlignedString(BASEVIDWIDTH - currentMenu->x, currentMenu->y + MP_ConnectMenu[mp_connect_room].alphaKey,
 		                         V_YELLOWMAP, (itemOn == mp_connect_room) ? "<Select to change>" : "<Unlisted Mode>");
 	else
@@ -11685,7 +11685,7 @@ static void M_ConnectMenu(INT32 choice)
 
 	// first page of servers
 	serverlistpage = 0;
-	if (ms_RoomId < 0)
+	if (cv_masterserver_room_id.value < 0)
 	{
 		M_RoomMenu(0); // Select a room instead of staring at an empty list
 		// This prevents us from returning to the modified game alert.
@@ -11781,7 +11781,7 @@ static void M_ChooseRoom(INT32 choice)
 #endif
 
 	if (choice == 0)
-		CV_SetValue(&cv_masterserver_room_id, 0);
+		CV_SetValue(&cv_masterserver_room_id, -1);
 	else
 	{
 		CV_SetValue(&cv_masterserver_room_id, roomIds[choice-1]);
@@ -11853,7 +11853,7 @@ static void M_DrawServerMenu(void)
 	if (currentMenu == &MP_ServerDef)
 	{
 		M_DrawLevelPlatterHeader(currentMenu->y - lsheadingheight/2, "Server settings", true, false);
-		if (ms_RoomId < 0)
+		if (cv_masterserver_room_id.value < 0)
 			V_DrawRightAlignedString(BASEVIDWIDTH - currentMenu->x, currentMenu->y + MP_ServerMenu[mp_server_room].alphaKey,
 			                         V_YELLOWMAP, (itemOn == mp_server_room) ? "<Select to change>" : "<Unlisted Mode>");
 		else
@@ -11949,7 +11949,7 @@ static void M_ServerOptions(INT32 choice)
 static void M_StartServerMenu(INT32 choice)
 {
 	(void)choice;
-	ms_RoomId = -1;
+	CV_SetValue(&cv_masterserver_room_id, -1);
 	levellistmode = LLM_CREATESERVER;
 	Newgametype_OnChange();
 	M_SetupNextMenu(&MP_ServerDef);
diff --git a/src/netcode/d_clisrv.c b/src/netcode/d_clisrv.c
index 067458852..6702e2591 100644
--- a/src/netcode/d_clisrv.c
+++ b/src/netcode/d_clisrv.c
@@ -663,7 +663,7 @@ void D_QuitNetGame(void)
 			if (netnodes[i].ingame)
 				HSendPacket(i, true, 0, 0);
 #ifdef MASTERSERVER
-		if (serverrunning && ms_RoomId > 0)
+		if (serverrunning && cv_masterserver_room_id.value > 0)
 			UnregisterServer();
 #endif
 	}
@@ -797,7 +797,7 @@ void SV_SpawnServer(void)
 		{
 			I_NetOpenSocket();
 #ifdef MASTERSERVER
-			if (ms_RoomId > 0)
+			if (cv_masterserver_room_id.value > 0)
 				RegisterServer();
 #endif
 		}
diff --git a/src/netcode/http-mserv.c b/src/netcode/http-mserv.c
index 4a0804984..8ce20af95 100644
--- a/src/netcode/http-mserv.c
+++ b/src/netcode/http-mserv.c
@@ -426,7 +426,7 @@ HMS_register (void)
 
 	char *title;
 
-	hms = HMS_connect(PROTO_V4, "rooms/%d/register", ms_RoomId);
+	hms = HMS_connect(PROTO_V4, "rooms/%d/register", cv_masterserver_room_id.value);
 
 	if (! hms)
 		return 0;
@@ -462,7 +462,7 @@ HMS_register (void)
 	if (!hms_allow_ipv6)
 		return ok;
 
-	hms = HMS_connect(PROTO_V6, "rooms/%d/register", ms_RoomId);
+	hms = HMS_connect(PROTO_V6, "rooms/%d/register", cv_masterserver_room_id.value);
 
 	if (! hms)
 		return 0;
diff --git a/src/netcode/mserv.c b/src/netcode/mserv.c
index fba36a3ba..f17db4b6e 100644
--- a/src/netcode/mserv.c
+++ b/src/netcode/mserv.c
@@ -67,9 +67,10 @@ consvar_t cv_masterserver = CVAR_INIT ("masterserver", "https://ds.ms.srb2.org/M
 consvar_t cv_servername = CVAR_INIT_WITH_CALLBACKS ("servername", "SRB2 server", CV_SAVE|CV_NETVAR|CV_CALL|CV_NOINIT|CV_ALLOWLUA, NULL, Update_parameters, ServerName_CanChange);
 
 consvar_t cv_masterserver_update_rate = CVAR_INIT ("masterserver_update_rate", "15", CV_SAVE|CV_CALL|CV_NOINIT, masterserver_update_rate_cons_t, Update_parameters);
-consvar_t cv_masterserver_room_id = CVAR_INIT ("masterserver_room_id", "0", CV_CALL, CV_Unsigned, RoomId_OnChange);
+CV_PossibleValue_t cv_masterserver_room_values[] = {{-1, "MIN"}, {999999999, "MAX"}, {0, NULL}};
+consvar_t cv_masterserver_room_id = CVAR_INIT ("masterserver_room_id", "-1", CV_CALL, cv_masterserver_room_values, RoomId_OnChange);
 
-INT16 ms_RoomId = 0;
+static INT16 ms_RoomId = -1;
 
 #if defined (MASTERSERVER) && defined (HAVE_THREADS)
 int           ms_QueryId;
@@ -449,7 +450,7 @@ void UnregisterServer(void)
 static boolean
 Online (void)
 {
-	return ( serverrunning && ms_RoomId > 0 );
+	return ( serverrunning && cv_masterserver_room_id.value > 0 );
 }
 
 static inline void SendPingToMasterServer(void)
diff --git a/src/netcode/mserv.h b/src/netcode/mserv.h
index 419c11a89..ed3c9b27b 100644
--- a/src/netcode/mserv.h
+++ b/src/netcode/mserv.h
@@ -71,11 +71,6 @@ extern consvar_t cv_masterserver_timeout;
 extern consvar_t cv_masterserver_debug;
 extern consvar_t cv_masterserver_token;
 
-// < 0 to not connect (usually -1) (offline mode)
-// == 0 to show all rooms, not a valid hosting room
-// anything else is whatever room the MS assigns to that number (online mode)
-extern INT16 ms_RoomId;
-
 #ifdef HAVE_THREADS
 extern int           ms_QueryId;
 extern I_mutex       ms_QueryId_mutex;