diff --git a/src/experimental/_impl/_differential_line_growth.scad b/src/experimental/_impl/_differential_line_growth.scad
index 7bcc7020..c7d44e32 100644
--- a/src/experimental/_impl/_differential_line_growth.scad
+++ b/src/experimental/_impl/_differential_line_growth.scad
@@ -1,8 +1,6 @@
 use <../../util/unit_vector.scad>;
 use <../../util/sum.scad>;
 
-ZERO_VT = [0, 0];
-
 ZERO_VTS = [undef, undef, [0, 0], [0, 0, 0]];
 
 function limit(vt, magnitude) =