diff --git a/src/terraform_gui.cpp b/src/terraform_gui.cpp
--- a/src/terraform_gui.cpp
+++ b/src/terraform_gui.cpp
@@ -80,12 +80,14 @@ static void GenerateRockyArea(TileIndex 
 		switch (GetTileType(tile)) {
 			case MP_TREES:
 				if (GetTreeGround(tile) == TREE_GROUND_SHORE) continue;
-				/* FALL THROUGH */
+				FALLTHROUGH;
+
 			case MP_CLEAR:
 				MakeClear(tile, CLEAR_ROCKS, 3);
 				break;
 
-			default: continue;
+			default:
+				continue;
 		}
 		MarkTileDirtyByTile(tile);
 		success = true;