diff --git a/src/experimental/tf_ring.scad b/src/experimental/tf_ring.scad
index a6b9950a..9e45f20f 100644
--- a/src/experimental/tf_ring.scad
+++ b/src/experimental/tf_ring.scad
@@ -8,7 +8,7 @@ use <experimental/tf_y_twist.scad>;
     angle: arc angle.
     twist: The number of degrees of through which the rectangle is twisted.
 */
-function tf_ring(size, point, radius, angle, twist = 0) = 
+function tf_ring(size, point, radius, angle = 360, twist = 0) = 
     let(
         yleng = size[1],
         a_step = angle / yleng,