diff --git a/functions.h b/functions.h
--- a/functions.h
+++ b/functions.h
@@ -205,7 +205,7 @@ bool CheckIfAuthorityAllows(TileIndex ti
 Town *ClosestTownFromTile(TileIndex tile, uint threshold);
 void ChangeTownRating(Town *t, int add, int max);
 
-int GetTownRadiusGroup(const Town *t, TileIndex tile);
+uint GetTownRadiusGroup(const Town* t, TileIndex tile);
 void ShowNetworkChatQueryWindow(byte desttype, byte dest);
 void ShowNetworkGiveMoneyWindow(byte player);
 void ShowNetworkNeedGamePassword(void);