diff --git a/src/modules/core.js b/src/modules/core.js
index e77c072..499c4e2 100644
--- a/src/modules/core.js
+++ b/src/modules/core.js
@@ -46,7 +46,8 @@ function createBoard(state, rules, max) {
     } else {
       nextState = evolve1d(prevState, rules);
     }
-    board = board.concat([nextState]);
+    // flat array
+    board.push(...nextState);
     prevState = nextState;
   }
   return board;
diff --git a/src/modules/picture.js b/src/modules/picture.js
index 117d358..6edda32 100644
--- a/src/modules/picture.js
+++ b/src/modules/picture.js
@@ -57,7 +57,7 @@ export function boardToPic(board) {
   const dead = board.cellProperties.deadColor;
   const img = new ImageData(board.width, board.height);
   const colors = [hexToRGB(live), hexToRGB(dead)];
-  board.grid.flat().reduce((acc, cell, index) => {
+  board.grid.reduce((acc, cell, index) => {
     const color = colors[(cell === 1) & 1];
     const i = index * 4;
     acc[i] = color[0];