diff --git a/src/angle_between.scad b/src/angle_between.scad
index 11ea2579..24aa6462 100644
--- a/src/angle_between.scad
+++ b/src/angle_between.scad
@@ -11,6 +11,6 @@
 use <_impl/_angle_between_impl.scad>;
 
 function angle_between(vt1, vt2, ccw = false) = 
-    !ccw ? acos((vt1 * vt2) / (norm(vt1) * norm(vt2))) :
+    !ccw ? acos((vt1 * vt2) / sqrt((vt1 * vt1) * (vt2 * vt2))) :
     len(vt1) == 2 ? angle_between_ccw_2d(vt1, vt2) : 
                     angle_between_ccw_3d(vt1, vt2);
\ No newline at end of file