diff --git a/examples/turtle/sierpinski_triangle.scad b/examples/turtle/sierpinski_triangle.scad
index 82e25df2..2d5c13cf 100644
--- a/examples/turtle/sierpinski_triangle.scad
+++ b/examples/turtle/sierpinski_triangle.scad
@@ -1,6 +1,5 @@
 include <line2d.scad>;
 include <polyline2d.scad>;
-include <turtle/turtle2d.scad>;
 include <turtle/t2d.scad>;
 
 side_leng = 100;
@@ -14,7 +13,7 @@ sierpinski_triangle(
 
 module triangle(t, side_leng, thickness) {    
     t2 = t2d(t, "forward", leng = side_leng);
-    t3 = t2d(t2, cmds = [
+    t3 = t2d(t2, [
         ["turn", 120],
         ["forward", side_leng]
     ]);
@@ -33,7 +32,7 @@ module sierpinski_triangle(t, side_leng, min_leng, thickness) {
     if(side_leng >= min_leng) { 
         half_leng = side_leng / 2;
         t2 = t2d(t, "forward", leng = half_leng); 
-        t3 = t2d(t, cmds = [
+        t3 = t2d(t, [
             ["turn", 60],
             ["forward", half_leng],
             ["turn", -60]
diff --git a/src/turtle/t2d.scad b/src/turtle/t2d.scad
index 3d0b1b93..9992f5db 100644
--- a/src/turtle/t2d.scad
+++ b/src/turtle/t2d.scad
@@ -57,6 +57,15 @@ function _t2d_set(t, point, angle, x, y) =
     !is_undef(y) ? _t2d_set_y(t, y) : 
     assert(false, "no target to set");
 
+function _t2d_cmd(t, cmd, point, angle, x, y, leng) = 
+    cmd == "set" ? _t2d_set(t, point, angle, x, y) :
+    cmd == "forward" ? _t2d_forward(t, leng) :
+    cmd == "turn" ? _t2d_turn(t, angle) :
+    cmd == "point" ? _t2d_get_pt(t) :
+    cmd == "angle" ? _t2d_get_angle(t) :
+    cmd == "x" ? _t2d_get_x(t) :
+    cmd == "y" ? _t2d_get_y(t) : assert(false, "unknown command");
+
 function _t2d_cmds(t, cmds, i = 0) = 
     i == len(cmds) ? t :
     let(
@@ -65,14 +74,7 @@ function _t2d_cmds(t, cmds, i = 0) =
     )
     _t2d_cmds(_t2d_cmdline(cmd, t, arg), cmds, i + 1);
 
-function t2d(t, cmd, cmds, point, angle, x, y, leng) =
+function t2d(t, cmd, point, angle, x, y, leng) =
     is_undef(t) ? _t2d_turtle(point, angle) : 
-    cmd == "set" ? _t2d_set(t, point, angle, x, y) :
-    cmd == "forward" ? _t2d_forward(t, leng) :
-    cmd == "turn" ? _t2d_turn(t, angle) :
-    cmd == "point" ? _t2d_get_pt(t) :
-    cmd == "angle" ? _t2d_get_angle(t) :
-    cmd == "x" ? _t2d_get_x(t) :
-    cmd == "y" ? _t2d_get_y(t) :
-    !is_undef(cmds) ? _t2d_cmds(t, cmds) :
-    assert(false, "unknown command");
\ No newline at end of file
+    is_string(cmd) ? _t2d_cmd(t, cmd, point, angle, x, y, leng) :
+                     _t2d_cmds(t, cmd) ;
\ No newline at end of file