diff --git a/src/experimental/tf_sphere.scad b/src/experimental/tf_sphere.scad
index 0a98c686..1b7abb35 100644
--- a/src/experimental/tf_sphere.scad
+++ b/src/experimental/tf_sphere.scad
@@ -10,13 +10,14 @@ function tf_sphere(size, point, radius, angle = [180, 360]) =
     let(
         x = point[0],
         y = point[1],
+        z = is_undef(point[2]) ? 0 : point[2],
         za = angle[0],  
         xa = angle[1], 
         xlen = size[0],
         ylen = size[1],
         za_step = za / ylen,
         rza = za_step * y,
-        rzpt = [radius * cos(rza), radius * sin(rza), 0],       
+        rzpt = [(radius + z) * cos(rza), (radius + z) * sin(rza), 0],       
         rxpt = rotate_p(rzpt, [xa / xlen * x, 0, 0])   
     )
     rxpt;
\ No newline at end of file