diff --git a/src/Environments/WorldEnvironment.js b/src/Environments/WorldEnvironment.js
index 039fcad..a57293e 100644
--- a/src/Environments/WorldEnvironment.js
+++ b/src/Environments/WorldEnvironment.js
@@ -14,7 +14,7 @@ class WorldEnvironment extends Environment{
         this.controller = new EnvironmentController(this, this.renderer.canvas);
         this.num_rows = Math.ceil(this.renderer.height / cell_size);
         this.num_cols = Math.ceil(this.renderer.width / cell_size);
-        this.grid_map = new GridMap(num_cols, num_rows, cell_size);
+        this.grid_map = new GridMap(this.num_cols, this.num_rows, cell_size);
         this.organisms = [];
         this.walls = [];
         this.total_mutability = 0;