diff --git a/mapserver/src/main.rs b/mapserver/src/main.rs
index 5ebb478..0e1ea76 100644
--- a/mapserver/src/main.rs
+++ b/mapserver/src/main.rs
@@ -13,7 +13,6 @@ enum Error {
 	Image(image::ImageError),
 	Io(std::io::Error),
 	Minetestmapper,
-	Todo,
 }
 
 #[async_std::main]
@@ -111,7 +110,13 @@ fn generate_tile(
 		} else {
 			if generate {
 				let (sender, receiver) = crossbeam_channel::bounded(0);
-				tasks_guard.insert((z, x, y), sender);
+				let lock_coord = if z > config.zoom_default {
+					// Generate 4 tiles at once
+					(z, x & !1, y & !1)
+				} else {
+					(z, x, y)
+				};
+				tasks_guard.insert(lock_coord, sender);
 				drop(tasks_guard);
 
 				let res: Result<(), Error> = try {
@@ -189,11 +194,116 @@ fn generate_tile(
 								Error::Image(e)
 							})?;
 						}
-						std::cmp::Ordering::Greater => Err(Error::Todo)?,
+						std::cmp::Ordering::Greater => {
+							let ntile_path =
+								get_dep_tile(z - 1, x / 2, y / 2, tasks.clone(), config.clone())?;
+							let ntile = image::open(ntile_path).map_err(Error::Image)?;
+							let ntile = image::imageops::resize(
+								&ntile,
+								config.tile_size as u32 * 2,
+								config.tile_size as u32 * 2,
+								image::imageops::Nearest,
+							);
+
+							image::imageops::crop_imm(
+								&ntile,
+								0,
+								0,
+								config.tile_size as u32,
+								config.tile_size as u32,
+							)
+							.to_image()
+							.save(format!(
+								"{}{}/{}/{}.png",
+								config.output_path, z, lock_coord.1, lock_coord.2
+							))
+							.map_err(|e| {
+								error!(
+									"Generating tile ({},{},{}): {}",
+									z, lock_coord.1, lock_coord.2, e
+								);
+								Error::Image(e)
+							})?;
+							image::imageops::crop_imm(
+								&ntile,
+								0,
+								config.tile_size as u32,
+								config.tile_size as u32,
+								config.tile_size as u32,
+							)
+							.to_image()
+							.save(format!(
+								"{}{}/{}/{}.png",
+								config.output_path,
+								z,
+								lock_coord.1,
+								lock_coord.2 + 1
+							))
+							.map_err(|e| {
+								error!(
+									"Generating tile ({},{},{}): {}",
+									z,
+									lock_coord.1,
+									lock_coord.2 + 1,
+									e
+								);
+								Error::Image(e)
+							})?;
+							image::imageops::crop_imm(
+								&ntile,
+								config.tile_size as u32,
+								0,
+								config.tile_size as u32,
+								config.tile_size as u32,
+							)
+							.to_image()
+							.save(format!(
+								"{}{}/{}/{}.png",
+								config.output_path,
+								z,
+								lock_coord.1 + 1,
+								lock_coord.2
+							))
+							.map_err(|e| {
+								error!(
+									"Generating tile ({},{},{}): {}",
+									z,
+									lock_coord.1 + 1,
+									lock_coord.2,
+									e
+								);
+								Error::Image(e)
+							})?;
+							image::imageops::crop_imm(
+								&ntile,
+								config.tile_size as u32,
+								config.tile_size as u32,
+								config.tile_size as u32,
+								config.tile_size as u32,
+							)
+							.to_image()
+							.save(format!(
+								"{}{}/{}/{}.png",
+								config.output_path,
+								z,
+								lock_coord.1 + 1,
+								lock_coord.2 + 1
+							))
+							.map_err(|e| {
+								error!(
+									"Generating tile ({},{},{}): {}",
+									z,
+									lock_coord.1 + 1,
+									lock_coord.2 + 1,
+									e
+								);
+								Error::Image(e)
+							})?;
+						}
 					}
 				};
 
-				tasks.write().remove(&(z, x, y));
+				tasks.write().remove(&lock_coord);
 				receiver.recv().ok();
 				res?;
 			} else {