diff --git a/src/map_func.h b/src/map_func.h
index 7d3e11cd80..21881058f2 100644
--- a/src/map_func.h
+++ b/src/map_func.h
@@ -451,7 +451,7 @@ debug_inline static uint TileY(TileIndex tile)
  */
 inline TileIndexDiff ToTileIndexDiff(TileIndexDiffC tidc)
 {
-	return (tidc.y << Map::LogX()) + tidc.x;
+	return TileDiffXY(tidc.x, tidc.y);
 }