diff -r b4785c8f3700 -r f6b4300cc2b0 tile.h
--- a/tile.h	Wed Oct 05 04:00:39 2005 +0000
+++ b/tile.h	Wed Oct 05 07:20:26 2005 +0000
@@ -99,7 +99,7 @@
 
 static inline bool IsTunnelTile(TileIndex tile)
 {
-	return IsTileType(tile, MP_TUNNELBRIDGE) && (_m[tile].m5 & 0xF0) == 0;
+	return IsTileType(tile, MP_TUNNELBRIDGE) && GB(_m[tile].m5, 4, 4) == 0;
 }
 
 static inline Owner GetTileOwner(TileIndex tile)