diff --git a/src/mserv.h b/src/mserv.h
index 6d91da643..5f9b8da5f 100644
--- a/src/mserv.h
+++ b/src/mserv.h
@@ -68,7 +68,7 @@ extern consvar_t cv_masterserver, cv_servername;
 // < 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)
-INT16 ms_RoomId;
+extern INT16 ms_RoomId;
 
 const char *GetMasterServerPort(void);
 const char *GetMasterServerIP(void);