diff --git a/src/minesweeper/Minesweeper.tsx b/src/minesweeper/Minesweeper.tsx
index f57b52c..4a166cb 100644
--- a/src/minesweeper/Minesweeper.tsx
+++ b/src/minesweeper/Minesweeper.tsx
@@ -75,12 +75,12 @@ function Minesweeper() {
 
     // Save game state on change
     useEffect(() => {
-        autorun((reaction) => {
+        const disposer = autorun(() => {
             const gamestate = game.Export();
             localStorage.setItem("gamestate", SerializeGameState(gamestate));
             console.log("Saved gamestate");
-            reaction.dispose();
         });
+        return () => disposer();
     }, [])
 
     const boardTileStyle = {
diff --git a/src/minesweeper/minesweeper-game.ts b/src/minesweeper/minesweeper-game.ts
index af46ed2..8458799 100644
--- a/src/minesweeper/minesweeper-game.ts
+++ b/src/minesweeper/minesweeper-game.ts
@@ -83,7 +83,7 @@ export class MinesweeperGame {
         return {
             BoardRows: this.boardRows,
             BoardColumns: this.boardColumns,
-            BoardData: this._board,
+            BoardData: this._board.slice(),
             MineCount: this.mineCount,
             Seed: this._seed,
             isOver: this.isOver,