diff --git a/src/app/editor.rs b/src/app/editor.rs
index ef69983..0a942ce 100644
--- a/src/app/editor.rs
+++ b/src/app/editor.rs
@@ -43,8 +43,8 @@ fn main() {
                         let x = ((x - left_panel_size.x as i32) / SPRITE_SIZE_I32) as usize;
                         let y = ((y - top_panel_size.y as i32) / SPRITE_SIZE_I32) as usize;
 
-                        if let Some(tile) = map.tile(y, x) {
-                            if tile == CollisionTile::empty() {
+                        if let Some(tile) = map.collision_tile(y, x) {
+                            if tile.is_empty() {
                                 map.set_tile(y, x, CollisionTile::full());
                             } else {
                                 map.set_tile(y, x, CollisionTile::empty());
diff --git a/src/engine/map/mod.rs b/src/engine/map/mod.rs
index 379ca36..7ff5c48 100644
--- a/src/engine/map/mod.rs
+++ b/src/engine/map/mod.rs
@@ -82,6 +82,16 @@ impl CollisionTile {
             from_bottom: true,
         }
     }
+
+    /// Tests whether a collision tile is full or not.
+    pub fn is_full(self) -> bool {
+        self.from_top && self.from_left && self.from_right && self.from_bottom
+    }
+
+    /// Tests whether a collision tile is empty or not.
+    pub fn is_empty(self) -> bool {
+        !self.from_top && !self.from_left && !self.from_right && !self.from_bottom
+    }
 }
 
 /// This struct represents a renderable tile linking to its part in the tileset texture.
@@ -94,79 +104,53 @@ impl GraphicTile {
     /// Creates the correct graphic tile depending on the neighbours.
     ///
     /// A none will be considered solid.
-    pub fn from_neighbour_options(
-        top_left: Option<CollisionTile>,
-        top: Option<CollisionTile>,
-        top_right: Option<CollisionTile>,
-        right: Option<CollisionTile>,
-        bottom_right: Option<CollisionTile>,
-        bottom: Option<CollisionTile>,
-        bottom_left: Option<CollisionTile>,
-        left: Option<CollisionTile>,
-    ) -> GraphicTile {
-        GraphicTile::from_neighbours(
-            top_left.unwrap_or_else(CollisionTile::full),
-            top.unwrap_or_else(CollisionTile::full),
-            top_right.unwrap_or_else(CollisionTile::full),
-            right.unwrap_or_else(CollisionTile::full),
-            bottom_right.unwrap_or_else(CollisionTile::full),
-            bottom.unwrap_or_else(CollisionTile::full),
-            bottom_left.unwrap_or_else(CollisionTile::full),
-            left.unwrap_or_else(CollisionTile::full),
-        )
+    pub fn from_neighbour_options(tiles: &[Option<CollisionTile>; 8]) -> GraphicTile {
+        GraphicTile::from_neighbours(&[
+            tiles[0].unwrap_or_else(CollisionTile::full),
+            tiles[1].unwrap_or_else(CollisionTile::full),
+            tiles[2].unwrap_or_else(CollisionTile::full),
+            tiles[3].unwrap_or_else(CollisionTile::full),
+            tiles[4].unwrap_or_else(CollisionTile::full),
+            tiles[5].unwrap_or_else(CollisionTile::full),
+            tiles[6].unwrap_or_else(CollisionTile::full),
+            tiles[7].unwrap_or_else(CollisionTile::full),
+        ])
     }
 
     /// Creates the correct graphic tile depending on the neighbours.
-    pub fn from_neighbours(
-        top_left: CollisionTile,
-        top: CollisionTile,
-        top_right: CollisionTile,
-        right: CollisionTile,
-        bottom_right: CollisionTile,
-        bottom: CollisionTile,
-        bottom_left: CollisionTile,
-        left: CollisionTile,
-    ) -> GraphicTile {
+    pub fn from_neighbours(tiles: &[CollisionTile; 8]) -> GraphicTile {
 
         let mut byte = 0;
 
-        if top_left != CollisionTile::full() ||
-           left     != CollisionTile::full() ||
-           top      != CollisionTile::full() {
+        if !tiles[7].is_full() || !tiles[0].is_full() || !tiles[1].is_full() {
             byte += 1;
         }
 
-        if top != CollisionTile::full() {
+        if !tiles[1].is_full() {
             byte += 2;
         }
 
-        if top_right != CollisionTile::full() ||
-           top       != CollisionTile::full() ||
-           right     != CollisionTile::full() {
+        if !tiles[1] .is_full() || !tiles[2].is_full() || !tiles[3].is_full() {
             byte += 4;
         }
 
-        if right != CollisionTile::full() {
+        if !tiles[3] .is_full() {
             byte += 8;
         }
 
-        if bottom_right != CollisionTile::full() ||
-           bottom       != CollisionTile::full() ||
-           right        != CollisionTile::full() {
+        if !tiles[3].is_full() || !tiles[4].is_full() || !tiles[5].is_full() {
             byte += 16;
         }
 
-        if bottom != CollisionTile::full() {
+        if !tiles[5].is_full() {
             byte += 32;
         }
 
-        if bottom_left != CollisionTile::full() ||
-           bottom      != CollisionTile::full() ||
-           left        != CollisionTile::full() {
+        if !tiles[5].is_full() || !tiles[6].is_full() || !tiles[7].is_full() {
             byte += 64;
         }
 
-        if left != CollisionTile::full() {
+        if !tiles[7] .is_full() {
             byte += 128;
         }
 
@@ -214,14 +198,34 @@ impl Drawable for PositionedTile {
     }
 }
 
-/// The map represents the tiles contained in a level.
+/// The content of a map that needs to be saved.
 #[derive(Serialize, Deserialize)]
+struct SaveMap {
+    /// The entrance point of the character in the map.
+    entrance: (usize, usize),
+
+    /// The collision tiles contained in the level.
+    collision_tiles: Matrix<CollisionTile>,
+}
+
+impl SaveMap {
+    /// Creates a map from the save map.
+    fn to_map(self) -> Map {
+        Map::from_entrance_and_collision_tiles(self.entrance, self.collision_tiles)
+    }
+}
+
+/// The map represents the tiles contained in a level.
+#[derive(Clone)]
 pub struct Map {
     /// The entrace point of the character in the map.
     entrance: (usize, usize),
 
-    /// The tiles contained in the level.
-    tiles: Matrix<(CollisionTile, GraphicTile)>,
+    /// The collision tiles contained in the level.
+    collision_tiles: Matrix<CollisionTile>,
+
+    /// The graphic tiles contained in the level.
+    graphic_tiles: Matrix<GraphicTile>,
 }
 
 impl Map {
@@ -237,21 +241,29 @@ impl Map {
         Map::from_collision_tiles(tiles)
     }
 
+    /// Creates a SaveMap from a map
+    fn save_map(&self) -> SaveMap {
+        SaveMap {
+            entrance: self.entrance,
+            collision_tiles: self.collision_tiles.clone(),
+        }
+    }
+
     /// Encodes the map into a binary format.
     pub fn encode(&self) -> Result<Vec<u8>> {
-        serialize(&self).map_err(Error::Encoding)
+        serialize(&self.save_map()).map_err(Error::Encoding)
     }
 
     /// Decodes a map from bytes.
     pub fn decode(content: &[u8]) -> Result<Map> {
-        deserialize(content).map_err(Error::Decoding)
+        deserialize(content).map(SaveMap::to_map).map_err(Error::Decoding)
     }
 
     /// Saves the map to a file.
     pub fn save<P: AsRef<Path>>(&self, path: P) -> Result<()> {
         let file = File::create(path.as_ref()).map_err(Error::Save)?;
         let mut writer = BufWriter::new(file);
-        serialize_into(&mut writer, &self).map_err(Error::Encoding)?;
+        serialize_into(&mut writer, &self.save_map()).map_err(Error::Encoding)?;
         Ok(())
     }
 
@@ -259,85 +271,83 @@ impl Map {
     pub fn load<P: AsRef<Path>>(path: P) -> Result<Map> {
         let file = File::open(path.as_ref()).map_err(Error::Load)?;
         let mut reader = BufReader::new(file);
-        Ok(deserialize_from(&mut reader).map_err(Error::Decoding)?)
+        Ok(deserialize_from(&mut reader).map(SaveMap::to_map).map_err(Error::Decoding)?)
     }
 
-    /// Creates a map from its tiles.
-    pub fn from_collision_tiles(tiles: Matrix<CollisionTile>) -> Map {
-        let rows = tiles.rows();
-        let cols = tiles.cols();
+    /// Creates a map from its entrance and collision tiles.
+    pub fn from_entrance_and_collision_tiles(e: (usize, usize), t: Matrix<CollisionTile>) -> Map {
+        let rows = t.rows();
+        let cols = t.cols();
 
-        let mut matrix =
-            Matrix::from_size(rows, cols, (CollisionTile::empty(), GraphicTile(None)));
+        let graphic_tiles = Matrix::from_size(rows, cols, GraphicTile(None));
 
-        for i in 0..rows {
-            for j in 0..cols {
-                let graphic = if tiles[(i, j)] == CollisionTile::full() {
-                    // TODO This is uggly
-                    // If there is an overflow, we should give None instead
-                    let (i, j) = (i as isize, j as isize);
+        let mut map = Map {
+            entrance: e,
+            collision_tiles: t,
+            graphic_tiles,
+        };
 
-                    GraphicTile::from_neighbour_options(
-                        tiles.get(((i - 1) as usize, (j - 1) as usize)).cloned(),
-                        tiles.get(((i    ) as usize, (j - 1) as usize)).cloned(),
-                        tiles.get(((i + 1) as usize, (j - 1) as usize)).cloned(),
-                        tiles.get(((i + 1) as usize, (j    ) as usize)).cloned(),
-                        tiles.get(((i + 1) as usize, (j + 1) as usize)).cloned(),
-                        tiles.get(((i    ) as usize, (j + 1) as usize)).cloned(),
-                        tiles.get(((i - 1) as usize, (j + 1) as usize)).cloned(),
-                        tiles.get(((i - 1) as usize, (j    ) as usize)).cloned(),
-                    )
-                } else {
-                    GraphicTile(None)
-                };
-
-                matrix[(i, j)] = (tiles[(i, j)], graphic);
+        for i in 0 .. rows {
+            for j in 0 .. cols {
+                map.graphic_tiles[(i, j)] = map.graphic_tile(i, j);
             }
         }
 
-        Map {
-            entrance: Map::find_entrance(&matrix),
-            tiles: matrix,
-        }
+        map
+    }
+
+    /// Creates a map from its tiles.
+    pub fn from_collision_tiles(collision_tiles: Matrix<CollisionTile>) -> Map {
+        let entrance = Map::find_entrance(&collision_tiles);
+        Map::from_entrance_and_collision_tiles(entrance, collision_tiles)
+    }
+
+    /// Creates the neighbours of a tile.
+    pub fn neighbours(&self, i: isize, j: isize) -> [Option<CollisionTile>; 8] {
+        [
+            self.collision_tiles.get_isize(i - 1, j - 1).cloned(),
+            self.collision_tiles.get_isize(i - 1, j    ).cloned(),
+            self.collision_tiles.get_isize(i - 1, j + 1).cloned(),
+            self.collision_tiles.get_isize(i    , j + 1).cloned(),
+            self.collision_tiles.get_isize(i + 1, j + 1).cloned(),
+            self.collision_tiles.get_isize(i + 1, j    ).cloned(),
+            self.collision_tiles.get_isize(i + 1, j - 1).cloned(),
+            self.collision_tiles.get_isize(i    , j - 1).cloned(),
+        ]
     }
 
     /// Returns the graphic tile corresponding to the collision tiles.
     pub fn graphic_tile(&self, i: usize, j: usize) -> GraphicTile {
-        if self.tiles[(i, j)].0 == CollisionTile::full() {
-            GraphicTile::from_neighbour_options(
-                self.tiles.get(((i - 1) as usize, (j - 1) as usize)).map(|x| x.0),
-                self.tiles.get(((i - 1) as usize, (j    ) as usize)).map(|x| x.0),
-                self.tiles.get(((i - 1) as usize, (j + 1) as usize)).map(|x| x.0),
-                self.tiles.get(((i    ) as usize, (j + 1) as usize)).map(|x| x.0),
-                self.tiles.get(((i + 1) as usize, (j + 1) as usize)).map(|x| x.0),
-                self.tiles.get(((i + 1) as usize, (j    ) as usize)).map(|x| x.0),
-                self.tiles.get(((i + 1) as usize, (j - 1) as usize)).map(|x| x.0),
-                self.tiles.get(((i    ) as usize, (j - 1) as usize)).map(|x| x.0),
-            )
+        if self.collision_tiles[(i, j)].is_full() {
+            GraphicTile::from_neighbour_options(&self.neighbours(i as isize, j as isize))
         } else {
             GraphicTile(None)
         }
     }
 
     /// Returns a tile of the map.
-    pub fn tile(&self, i: usize, j: usize) -> Option<CollisionTile> {
-        self.tiles.get((i, j)).map(|x| x.0)
+    pub fn collision_tile(&self, i: usize, j: usize) -> Option<CollisionTile> {
+        self.collision_tiles.get((i, j)).cloned()
     }
 
     /// Changes a tile of the map.
     pub fn set_tile(&mut self, i: usize, j: usize, tile: CollisionTile) {
-        self.tiles[(i, j)] = (tile, GraphicTile(None));
+        // Change the collision tile
+        self.collision_tiles[(i, j)] = tile;
+
+        // Refresh the current graphic tile and their neighbours
         for i in (i - 1) ..= (i + 1) {
             for j in (j - 1) ..= (j + 1) {
-                if self.tiles.get((i, j)).is_some() {
-                    self.tiles[(i, j)].1 = self.graphic_tile(i, j);
+                let new_tile = self.graphic_tile(i, j);
+                if let Some(tile) = self.graphic_tiles.get_mut((i, j)) {
+                    *tile = new_tile;
                 }
             }
         }
     }
 
     /// Finds a possible entrance.
-    pub fn find_entrance(tiles: &Matrix<(CollisionTile, GraphicTile)>) -> (usize, usize) {
+    pub fn find_entrance(tiles: &Matrix<CollisionTile>) -> (usize, usize) {
         (tiles.rows() - 5, 1)
     }
 
@@ -349,20 +359,20 @@ impl Map {
     /// Returns an iterator to the positioned tiles.
     pub fn at(&self, row: usize, col: usize) -> PositionedTile {
         PositionedTile {
-            collision: self.tiles[(row, col)].0,
-            graphic: self.tiles[(row, col)].1,
+            collision: self.collision_tiles[(row, col)],
+            graphic: self.graphic_tiles[(row, col)],
             position: (col as f32 * SPRITE_SIZE_F32, row as f32 * SPRITE_SIZE_F32),
         }
     }
 
     /// Returns the number of rows of the map.
     pub fn rows(&self) -> usize {
-        self.tiles.rows()
+        self.collision_tiles.rows()
     }
 
     /// Returns the number of columns of the map.
     pub fn cols(&self) -> usize {
-        self.tiles.cols()
+        self.collision_tiles.cols()
     }
 
     /// Checks whether the bounding box collides with elements of the map.
@@ -376,8 +386,8 @@ impl Map {
 
         let mut damage = Damage::None;
 
-        let cols = self.tiles.cols() - 1;
-        let rows = self.tiles.rows() - 1;
+        let cols = self.collision_tiles.cols() - 1;
+        let rows = self.collision_tiles.rows() - 1;
 
         let min_col = clamp(new.left / SPRITE_SIZE_F32, 0.0, cols as f32) as usize;
         let min_row = clamp(new.top / SPRITE_SIZE_F32, 0.0, rows as f32) as usize;
@@ -401,7 +411,7 @@ impl Map {
                 }
 
                 // Collisions between feet and ground
-                if self.tiles[(row, col)].0.from_top
+                if self.collision_tiles[(row, col)].from_top
                     && old.top + old.height <= tile_top
                     && new.top + new.height >= tile_top
                 {
@@ -414,7 +424,7 @@ impl Map {
                 }
 
                 // Collisions between right and right wall
-                if self.tiles[(row, col)].0.from_left
+                if self.collision_tiles[(row, col)].from_left
                     && old.left + old.width <= tile_left
                     && new.left + new.width >= tile_left
                 {
@@ -427,7 +437,7 @@ impl Map {
                 }
 
                 // Collisions between left and left wall
-                if self.tiles[(row, col)].0.from_right
+                if self.collision_tiles[(row, col)].from_right
                     && old.left >= tile_left + SPRITE_SIZE_F32
                     && new.left <= tile_left + SPRITE_SIZE_F32
                 {
@@ -440,7 +450,7 @@ impl Map {
                 }
 
                 // Collisions between head and roof
-                if self.tiles[(row, col)].0.from_bottom
+                if self.collision_tiles[(row, col)].from_bottom
                     && old.top >= tile_top + SPRITE_SIZE_F32
                     && new.top <= tile_top + SPRITE_SIZE_F32
                 {
@@ -463,8 +473,8 @@ impl Map {
         }
 
         // Collision between the player and the void
-        if new.top > self.tiles.rows() as f32 * SPRITE_SIZE_F32 {
-            new.top = self.tiles.rows() as f32 * SPRITE_SIZE_F32;
+        if new.top > self.collision_tiles.rows() as f32 * SPRITE_SIZE_F32 {
+            new.top = self.collision_tiles.rows() as f32 * SPRITE_SIZE_F32;
             collision_y = true;
             damage = Damage::Death;
         }
diff --git a/src/engine/math/mod.rs b/src/engine/math/mod.rs
index 475db8b..837b375 100644
--- a/src/engine/math/mod.rs
+++ b/src/engine/math/mod.rs
@@ -27,7 +27,7 @@ pub fn duration_as_f32(duration: &Duration) -> f32 {
 }
 
 /// A generic matrix type, useful for levels.
-#[derive(Serialize, Deserialize)]
+#[derive(Serialize, Deserialize, Clone)]
 pub struct Matrix<T> {
     /// The number of rows of the matrix.
     rows: usize,
@@ -77,6 +77,25 @@ impl<T> Matrix<T> {
             None
         }
     }
+
+
+    /// Returns the tile if any, none otherwise.
+    pub fn get_isize(&self, row: isize, col: isize) -> Option<&T> {
+        if row >= 0 && col >= 0 && (row as usize) < self.rows && (col as usize) < self.cols {
+            Some(&self[(row as usize, col as usize)])
+        } else {
+            None
+        }
+    }
+
+    /// Returns a mutable reference to the tile if any.
+    pub fn get_mut(&mut self, (row, col): (usize, usize)) -> Option<&mut T> {
+        if row < self.rows && col < self.cols {
+            Some(&mut self[(row, col)])
+        } else {
+            None
+        }
+    }
 }
 
 impl<T> Index<(usize, usize)> for Matrix<T> {