diff --git a/src/ship_cmd.cpp b/src/ship_cmd.cpp
--- a/src/ship_cmd.cpp
+++ b/src/ship_cmd.cpp
@@ -317,11 +317,6 @@ void Ship::UpdateDeltaXY(Direction direc
 	this->z_extent      = 6;
 }
 
-static const TileIndexDiffC _ship_leave_depot_offs[] = {
-	{-1,  0},
-	{ 0, -1}
-};
-
 static bool CheckShipLeaveDepot(Ship *v)
 {
 	if (!v->IsChainInDepot()) return false;
@@ -337,9 +332,9 @@ static bool CheckShipLeaveDepot(Ship *v)
 	Axis axis = GetShipDepotAxis(tile);
 
 	DiagDirection north_dir = ReverseDiagDir(AxisToDiagDir(axis));
-	TileIndex north_neighbour = TILE_ADD(tile, ToTileIndexDiff(_ship_leave_depot_offs[axis]));
+	TileIndex north_neighbour = TILE_ADD(tile, TileOffsByDiagDir(north_dir));
 	DiagDirection south_dir = AxisToDiagDir(axis);
-	TileIndex south_neighbour = TILE_ADD(tile, -2 * ToTileIndexDiff(_ship_leave_depot_offs[axis]));
+	TileIndex south_neighbour = TILE_ADD(tile, 2 * TileOffsByDiagDir(south_dir));
 
 	TrackBits north_tracks = DiagdirReachesTracks(north_dir) & GetTileShipTrackStatus(north_neighbour);
 	TrackBits south_tracks = DiagdirReachesTracks(south_dir) & GetTileShipTrackStatus(south_neighbour);