diff --git a/src/archimedean_spiral.scad b/src/archimedean_spiral.scad
index 18ef215b..a638bdde 100644
--- a/src/archimedean_spiral.scad
+++ b/src/archimedean_spiral.scad
@@ -9,8 +9,11 @@
 **/ 
 
 function _radian_step(b, theta, l) =
-    let(r_square = pow(b * theta, 2))
-    acos((2 * r_square - pow(l, 2)) / (2 * r_square)) / 180 * PI;
+    let(
+        r_square = pow(b * theta, 2),
+        double_r_square = 2 * r_square
+    )
+    acos((double_r_square - pow(l, 2)) / double_r_square) / 180 * PI;
 
 function _find_radians(b, point_distance, radians, n, count = 1) =
     let(pre_radians = radians[count - 1])