diff --git a/src/Mono.cs b/src/Mono.cs
index 37ad4cf..9d31865 100644
--- a/src/Mono.cs
+++ b/src/Mono.cs
@@ -127,14 +127,8 @@ static class Mono
             return;
         }
 
-        XYZi next_pos = snake[0] + snake_dir;
-        XYZi inset_pos = new(
-            next_pos.x - Maths.sign(next_pos.x),
-            next_pos.y - Maths.sign(next_pos.y),
-            next_pos.z - Maths.sign(next_pos.z)
-        );
-        bool around_box = s_array.InRange(inset_pos);
-        if (!around_box)
+        bool in_or_around_box = s_array.InRange(snake[0] + snake_dir);
+        if (!in_or_around_box)
         {
             return;
         }