diff --git a/src/experimental/fibonacci_lattice.scad b/src/experimental/fibonacci_lattice.scad
index 710d352c..6ddc5391 100644
--- a/src/experimental/fibonacci_lattice.scad
+++ b/src/experimental/fibonacci_lattice.scad
@@ -1,4 +1,4 @@
-function fibonacci_lattice(n, radius, dir = "CT_CLK") =
+function fibonacci_lattice(n, radius = 1, dir = "CT_CLK") =
     let(
         toDegrees = 180 / PI,
         phi = PI * (3 - sqrt(5)),