diff --git a/src/function_grapher.scad b/src/function_grapher.scad
index b769745e..7968508e 100644
--- a/src/function_grapher.scad
+++ b/src/function_grapher.scad
@@ -9,6 +9,8 @@
 **/ 
 
 use <util/reverse.scad>;
+use <polyline3d.scad>;
+use <hull_polyline3d.scad>;
 
 module function_grapher(points, thickness, style = "FACES", slicing = "SLASH") {