diff --git a/src/heightmap.cpp b/src/heightmap.cpp
--- a/src/heightmap.cpp
+++ b/src/heightmap.cpp
@@ -364,16 +364,16 @@ static void GrayscaleToMapHeights(uint i
 				assert(img_row < img_height);
 				assert(img_col < img_width);
 
-				/* The height in 1/255ths. */
+				/* The height in 1/256ths. */
 				uint heightmap_height = map[img_row * img_width + img_col];
 
-				/* The height in 1/255ths of the maximum height. */
-				heightmap_height *= _settings_game.construction.max_heightlevel;
+				/* The height in 1/256ths of the maximum height. */
+				heightmap_height *= (1 + _settings_game.construction.max_heightlevel);
 
 				/* Scaling should not alter the coastline, thus values in the interval ]0..1] result in a heightlevel of 1 */
-				if (IsInsideMM(heightmap_height, 1, UINT8_MAX)) heightmap_height = UINT8_MAX;
+				if (IsInsideMM(heightmap_height, 1, 256)) heightmap_height = 256;
 
-				SetTileHeight(tile, heightmap_height / UINT8_MAX);
+				SetTileHeight(tile, heightmap_height / 256);
 			}
 			/* Only clear the tiles within the map area. */
 			if (IsInnerTile(tile)) {