diff --git a/src/town_cmd.cpp b/src/town_cmd.cpp
--- a/src/town_cmd.cpp
+++ b/src/town_cmd.cpp
@@ -306,7 +306,7 @@ static void DrawTile_Town(TileInfo *ti)
 	}
 }
 
-static int GetSlopePixelZ_Town(TileIndex tile, uint x, uint y)
+static int GetSlopePixelZ_Town(TileIndex tile, uint x, uint y, bool ground_vehicle)
 {
 	return GetTileMaxPixelZ(tile);
 }