diff --git a/src/maze/_impl/_mz_hex_walls.scad b/src/maze/_impl/_mz_hex_walls.scad
index 7920855d..0ad241db 100644
--- a/src/maze/_impl/_mz_hex_walls.scad
+++ b/src/maze/_impl/_mz_hex_walls.scad
@@ -36,14 +36,14 @@ function _build_cell(cell_radius, cell) =
     let(
         x = _get_x(cell),
         y = _get_y(cell),
-        walls = concat(
-            _is_mask(cell) ? [] : _row_wall(cell_radius, x, y),
-            [_is_top_wall(cell) || _is_top_right_wall(cell) ? _top(cell_radius) : []],
-            [_is_right_wall(cell) || _is_top_right_wall(cell) ? _right_wall(cell_radius, x) : []]
-        ),
+        walls = [
+            if(!_is_mask(cell)) each _row_wall(cell_radius, x, y),
+            if(_is_top_wall(cell) || _is_top_right_wall(cell)) _top(cell_radius),
+            if(_is_right_wall(cell) || _is_top_right_wall(cell)) _right_wall(cell_radius, x)
+        ],
         cell_p = _cell_position(cell_radius, x, y)
     )
     [
-        for(wall = walls)
-        if(wall != []) [for(p = wall) cell_p + p]
+        for(wall = walls) 
+        [for(p = wall) cell_p + p]
     ];
diff --git a/src/maze/_impl/_mz_square_walls_impl.scad b/src/maze/_impl/_mz_square_walls_impl.scad
index e79e08ba..7095f02d 100644
--- a/src/maze/_impl/_mz_square_walls_impl.scad
+++ b/src/maze/_impl/_mz_square_walls_impl.scad
@@ -1,9 +1,8 @@
 use <_mz_square_comm.scad>;
 
 function _square_walls(cell, cell_width) = 
-    let(
-        loc = [get_x(cell), get_y(cell)] * cell_width,
-        top = top_wall(cell) || top_right_wall(cell) ? [[0, cell_width] + loc, [cell_width, cell_width] + loc] : [],
-        right = right_wall(cell) || top_right_wall(cell) ? [[cell_width, cell_width] + loc, [cell_width, 0] + loc] : []
-    )
-    concat(top, right); 
+    let(loc = [get_x(cell), get_y(cell)] * cell_width)
+    [
+        if(top_wall(cell) || top_right_wall(cell)) each [[0, cell_width] + loc, [cell_width, cell_width] + loc],
+        if(right_wall(cell) || top_right_wall(cell)) each [[cell_width, cell_width] + loc, [cell_width, 0] + loc]
+    ];