diff --git a/half-earth/scripts/WorldGrid.cs b/half-earth/scripts/WorldGrid.cs
index 5a06ef9..a59855d 100644
--- a/half-earth/scripts/WorldGrid.cs
+++ b/half-earth/scripts/WorldGrid.cs
@@ -47,6 +47,9 @@ public class WorldGrid : Node2D
 
     public void ToggleTileHighlight(int x, int y)
     {
+        if (!IsInBounds(x, y))
+            return;
+
         _tiles[x, y].isHighlighted ^= true;
     }