diff --git a/src/in_shape.scad b/src/in_shape.scad
index e4b1795a..2041c0af 100644
--- a/src/in_shape.scad
+++ b/src/in_shape.scad
@@ -8,6 +8,7 @@
 *
 **/
 
+include <__private__/__to3d.scad>;
 include <__private__/__lines_from.scad>;
 include <__private__/__in_line.scad>;