diff --git a/packages/topdown/src/resources/tiles.js b/packages/topdown/src/resources/tiles.js
index 4d5838d..f92d96f 100644
--- a/packages/topdown/src/resources/tiles.js
+++ b/packages/topdown/src/resources/tiles.js
@@ -215,8 +215,7 @@ export default (latus) => {
 
     tileAt([x, y]) {
       const [w, h] = this.size;
-      const index = y * w + x;
-      return x < 0 || x >= w || y < 0 || y >= h ? undefined : this.data[index];
+      return x < 0 || x >= w || y < 0 || y >= h ? undefined : this.data[y * w + x];
     }
 
     toNetwork() {