diff --git a/src/industry_cmd.cpp b/src/industry_cmd.cpp
--- a/src/industry_cmd.cpp
+++ b/src/industry_cmd.cpp
@@ -928,7 +928,7 @@ static void PlantFarmField(TileIndex til
 	/* check the amount of bad tiles */
 	count = 0;
 	BEGIN_TILE_LOOP(cur_tile, size_x, size_y, tile)
-		TILE_ASSERT(cur_tile);
+		assert(cur_tile < MapSize());
 		count += IsBadFarmFieldTile(cur_tile);
 	END_TILE_LOOP(cur_tile, size_x, size_y, tile)
 	if (count * 2 >= size_x * size_y) return;
@@ -940,7 +940,7 @@ static void PlantFarmField(TileIndex til
 
 	/* make field */
 	BEGIN_TILE_LOOP(cur_tile, size_x, size_y, tile)
-		TILE_ASSERT(cur_tile);
+		assert(cur_tile < MapSize());
 		if (!IsBadFarmFieldTile2(cur_tile)) {
 			MakeField(cur_tile, field_type, industry);
 			SetClearCounter(cur_tile, counter);
diff --git a/src/map_func.h b/src/map_func.h
--- a/src/map_func.h
+++ b/src/map_func.h
@@ -18,11 +18,6 @@ extern uint _map_tile_mask;
  */
 
 #define TILE_MASK(x) ((x) & _map_tile_mask)
-/**
- * Asserts when the tile is outside of the map.
- * @param x the tile to check
- */
-#define TILE_ASSERT(x) assert(TILE_MASK(x) == (x));
 
 /**
  * Pointer to the tile-array.
diff --git a/src/town_cmd.cpp b/src/town_cmd.cpp
--- a/src/town_cmd.cpp
+++ b/src/town_cmd.cpp
@@ -818,7 +818,7 @@ no_slope:
 
 static bool TerraformTownTile(TileIndex tile, int edges, int dir)
 {
-	TILE_ASSERT(tile);
+	assert(tile < MapSize());
 
 	CommandCost r = DoCommand(tile, edges, dir, DC_AUTO | DC_NO_WATER, CMD_TERRAFORM_LAND);
 	if (CmdFailed(r) || r.GetCost() >= (_price.terraform + 2) * 8) return false;
@@ -828,7 +828,7 @@ static bool TerraformTownTile(TileIndex 
 
 static void LevelTownLand(TileIndex tile)
 {
-	TILE_ASSERT(tile);
+	assert(tile < MapSize());
 
 	/* Don't terraform if land is plain or if there's a house there. */
 	if (IsTileType(tile, MP_HOUSE)) return;
@@ -1027,7 +1027,7 @@ static void GrowTownInTile(TileIndex *ti
 	RoadBits rcmd = ROAD_NONE;  // RoadBits for the road construction command
 	TileIndex tile = *tile_ptr; // The main tile on which we base our growth
 
-	TILE_ASSERT(tile);
+	assert(tile < MapSize());
 
 	if (cur_rb == ROAD_NONE) {
 		/* Tile has no road. First reset the status counter
@@ -1195,7 +1195,7 @@ static int GrowTownAtRoad(Town *t, TileI
 	 */
 	DiagDirection target_dir = DIAGDIR_END; // The direction in which we want to extend the town
 
-	TILE_ASSERT(tile);
+	assert(tile < MapSize());
 
 	/* Number of times to search.
 	 * Better roads, 2X2 and 3X3 grid grow quite fast so we give
diff --git a/src/unmovable_cmd.cpp b/src/unmovable_cmd.cpp
--- a/src/unmovable_cmd.cpp
+++ b/src/unmovable_cmd.cpp
@@ -452,7 +452,7 @@ void GenerateUnmovables()
 				MakeLighthouse(tile);
 				IncreaseGeneratingWorldProgress(GWP_UNMOVABLE);
 				lighthouses_to_build--;
-				TILE_ASSERT(tile);
+				assert(tile < MapSize());
 				break;
 			}
 			tile = AddTileIndexDiffCWrap(tile, TileIndexDiffCByDiagDir(dir));