diff --git a/src/main.zig b/src/main.zig
index a05b4a4..df84c86 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -172,6 +172,7 @@ var camera = Vec2{ 0, 0 };
 const Coin = struct { pos: Pos, sprite: Sprite, anim: Anim, area: AABB };
 var coins = std.BoundedArray(Coin, 10).init(0) catch unreachable;
 var score: u8 = 0;
+var solids_mutable = assets.solid;
 
 const anim_store = struct {
     const stand = Anim.frame(8);
@@ -203,7 +204,7 @@ export fn start() void {
     particles = ParticleSystem.init();
 
     circuit = Circuit.init(&assets.conduit, assets.conduit_size);
-    map = Map.init(&assets.solid, assets.solid_size);
+    map = Map.init(&solids_mutable, assets.solid_size);
 
     camera = @divTrunc(assets.spawn, @splat(2, @as(i32, 20))) * @splat(2, @as(i32, 20));
 
@@ -489,7 +490,7 @@ fn updateCircuit() void {
         const cellEnd = util.world2cell(end.pos);
         if (circuit.isEnabled(cellBegin) or circuit.isEnabled(cellEnd)) wire.enabled = true;
     }
-    map.reset();
+    map.reset(&assets.solid);
     const enabledDoors = circuit.enabledDoors();
     for (enabledDoors.constSlice()) |door| {
         map.set_cell(door, 0);
diff --git a/src/map.zig b/src/map.zig
index deca3b6..f66ffdf 100644
--- a/src/map.zig
+++ b/src/map.zig
@@ -19,33 +19,31 @@ const tilemap_width = 16;
 const tilemap_height = 16;
 const tilemap_stride = 128;
 
-const UpdateMap = util.Map(Cell, u8, MAXCELLS);
-
-tiles: []const u8,
-tile_updates: UpdateMap,
+tiles: []u8,
 map_size: Vec2,
 
-pub fn init(map: []const u8, map_size: Vec2) @This() {
+pub fn init(map: []u8, map_size: Vec2) @This() {
     var this = @This(){
         .tiles = map,
-        .tile_updates = UpdateMap.init(),
         .map_size = map_size,
     };
     return this;
 }
 
 pub fn set_cell(this: *@This(), cell: Cell, tile: u8) void {
-    this.tile_updates.set(cell, tile);
+    const x = cell[0];
+    const y = cell[1];
+    if (x < 0 or x > this.map_size[0] or y < 0 or y > this.map_size[1]) unreachable;
+    const i = x + y * this.map_size[0];
+    this.tiles[@intCast(usize, i)] = tile;
 }
 
-pub fn reset(this: *@This()) void {
-    var updates = this.tile_updates.values.slice();
-    for (this.tile_updates.keys.slice()) |key, i| {
-        updates[i] = this.get_cell_raw(key).?;
-    }
+pub fn reset(this: *@This(), initialState: []const u8) void {
+    std.debug.assert(initialState.len == this.tiles.len);
+    std.mem.copy(u8, this.tiles, initialState);
 }
 
-fn get_cell_raw(this: @This(), cell: Cell) ?u8 {
+pub fn get_cell(this: @This(), cell: Cell) ?u8 {
     const x = cell[0];
     const y = cell[1];
     if (x < 0 or x > this.map_size[0] or y < 0 or y > this.map_size[1]) return null;
@@ -53,11 +51,6 @@ fn get_cell_raw(this: @This(), cell: Cell) ?u8 {
     return this.tiles[@intCast(u32, i)];
 }
 
-pub fn get_cell(this: @This(), cell: Cell) ?u8 {
-    if (this.tile_updates.get_const(cell)) |tile| return tile;
-    return this.get_cell_raw(cell);
-}
-
 pub fn draw(this: @This(), offset: Vec2) void {
     w4.DRAW_COLORS.* = 0x0210;
     var y: usize = 0;