--- a/industry_cmd.c	Sun Aug 06 08:23:19 2006 +0000
+++ b/industry_cmd.c	Sun Aug 06 16:32:49 2006 +0000
@@ -267,9 +267,9 @@
 	}
 }
 
-static uint GetSlopeZ_Industry(const TileInfo *ti)
+static uint GetSlopeZ_Industry(TileIndex tile, uint x, uint y)
 {
-	return ti->z + (ti->tileh == SLOPE_FLAT ? 0 : TILE_HEIGHT);
+	return GetTileMaxZ(tile);
 }
 
 static Slope GetSlopeTileh_Industry(TileIndex tile, Slope tileh)