diff --git a/src/road_cmd.cpp b/src/road_cmd.cpp
--- a/src/road_cmd.cpp
+++ b/src/road_cmd.cpp
@@ -1886,7 +1886,7 @@ void UpdateNearestTownForRoadTiles(bool 
 	}
 }
 
-static int GetSlopePixelZ_Road(TileIndex tile, uint x, uint y)
+static int GetSlopePixelZ_Road(TileIndex tile, uint x, uint y, bool ground_vehicle)
 {
 
 	if (IsNormalRoad(tile)) {