diff --git a/src/landscape.cpp b/src/landscape.cpp
index 544a41876b..6e69c0041f 100644
--- a/src/landscape.cpp
+++ b/src/landscape.cpp
@@ -894,7 +894,7 @@ static void GenerateTerrain(int type, uint flag)
 				for (uint w_cur = w; w_cur != 0; --w_cur) {
 					if (GB(*p, 0, 4) >= TileHeight(tile_cur)) SetTileHeight(tile_cur, GB(*p, 0, 4));
 					p++;
-					tile_cur++;
+					tile_cur += TileDiffXY(1, 0);
 				}
 				tile += TileDiffXY(0, 1);
 			} while (--h != 0);
@@ -921,7 +921,7 @@ static void GenerateTerrain(int type, uint flag)
 				for (uint w_cur = w; w_cur != 0; --w_cur) {
 					if (GB(*p, 0, 4) >= TileHeight(tile_cur)) SetTileHeight(tile_cur, GB(*p, 0, 4));
 					p++;
-					tile_cur--;
+					tile_cur -= TileDiffXY(1, 0);
 				}
 				tile += TileDiffXY(0, 1);
 			} while (--h != 0);