--- a/src/industry_cmd.cpp
+++ b/src/industry_cmd.cpp
@@ -159,7 +159,6 @@
 
 		/* Remove the farmland and convert it to regular tiles over time. */
 		TILE_AREA_LOOP(tile_cur, ta) {
-			tile_cur = TILE_MASK(tile_cur);
 			if (IsTileType(tile_cur, MP_CLEAR) && IsClearGround(tile_cur, CLEAR_FIELDS) &&
 					GetIndustryIndexOfField(tile_cur) == this->index) {
 				SetIndustryIndexOfField(tile_cur, INVALID_INDUSTRY);

--- a/src/map_func.h
+++ b/src/map_func.h
@@ -334,30 +334,6 @@
 uint DistanceFromEdgeDir(TileIndex, DiagDirection); ///< distance from the map edge in given direction
 
 /**
- * A loop which iterates to a square of tiles
- *
- * This macro starts 2 nested loops which iterates over a square of tiles.
- *
- * @param var The name of the variable which contains the current tile
- * @param w The width (x-width) of the square
- * @param h The heigth (y-width) of the square
- * @param tile The start tile of the square
- */
-#define TILE_LOOP(var, w, h, tile)                                                      \
-	for (uint var = tile, cur_h = (h); cur_h > 0; --cur_h, var += TileDiffXY(0, 1) - (w)) \
-		for (uint cur_w = (w); cur_w > 0; --cur_w, var++)
-
-/**
- * A loop which iterates over the tiles of a TileArea
- *
- * This macro starts 2 nested loops which iterates over a square of tiles.
- *
- * @param var The name of the variable which contains the current tile
- * @param ta  The tile area to search over
- */
-#define TILE_AREA_LOOP(var, ta) TILE_LOOP(var, ta.w, ta.h, ta.tile)
-
-/**
  * Convert a DiagDirection to a TileIndexDiff
  *
  * @param dir The DiagDirection

--- a/src/tilearea_type.h
+++ b/src/tilearea_type.h
@@ -60,4 +60,58 @@
 	}
 };
 
+/** Iterator to iterate over a tile area (rectangle) of the map. */
+class TileIterator {
+private:
+	TileIndex tile; ///< The current tile we are at.
+	int w;          ///< The width of the iterated area.
+	int x;          ///< The current 'x' position in the rectangle.
+	int y;          ///< The current 'y' position in the rectangle.
+
+public:
+	/**
+	 * Construct the iterator.
+	 * @param ta Area, i.e. begin point and width/height of to-be-iterated area.
+	 */
+	TileIterator(const TileArea &ta) : tile(ta.tile), w(ta.w), x(ta.w), y(ta.h)
+	{
+		if (ta.w == 0 || ta.h == 0) this->tile = INVALID_TILE;
+	}
+
+	/**
+	 * Get the tile we are currently at.
+	 * @return The tile we are at, or INVALID_TILE when we're done.
+	 */
+	FORCEINLINE operator TileIndex () const
+	{
+		return this->tile;
+	}
+
+	/**
+	 * Move ourselves to the next tile in the rectange on the map.
+	 */
+	FORCEINLINE TileIterator& operator ++()
+	{
+		assert(this->tile != INVALID_TILE);
+
+		if (--this->x > 0) {
+			this->tile++;
+		} else if (--this->y > 0) {
+			this->x = this->w;
+			this->tile += TileDiffXY(1, 1) - this->w;
+		} else {
+			this->tile = INVALID_TILE;
+		}
+		return *this;
+	}
+};
+
+/**
+ * A loop which iterates over the tiles of a TileArea.
+ * @param var The name of the variable which contains the current tile.
+ *            This variable will be allocated in this \c for of this loop.
+ * @param ta  The tile area to search over.
+ */
+#define TILE_AREA_LOOP(var, ta) for (TileIterator var(ta); var != INVALID_TILE; ++var)
+
 #endif /* TILEAREA_TYPE_H */