diff --git a/src/experimental/_impl/_lsystem2_impl.scad b/src/experimental/_impl/_lsystem2_impl.scad
index 867c72c8..979120c4 100644
--- a/src/experimental/_impl/_lsystem2_impl.scad
+++ b/src/experimental/_impl/_lsystem2_impl.scad
@@ -10,23 +10,23 @@ function _join(strs) =
     let(leng = len(strs))
     [for(i = 0, s = strs[0]; i < leng; i = i + 1, s = str(s, strs[i])) s][leng - 1];
 
-function c_or_v(c, v, rand_n, rule, derived_pr, leng, i = 0) =
+function c_or_v(c, v, rand_n, rule, rule_pr, leng, i = 0) =
     i == leng ? c : (
         let(idx = search([v[i]], rule, num_returns_per_match=0, index_col_num = 1)[0][0])
-        rand_n < derived_pr[idx - 1] ? v[i] : c_or_v(c, v, rand_n, rule, derived_pr, leng, i + 1)
+        rand_n < rule_pr[idx - 1] ? v[i] : c_or_v(c, v, rand_n, rule, rule_pr, leng, i + 1)
     );
 
-function _derive1_p(base, rule, derived_pr) = 
+function _derive1_p(base, rule, rule_pr) = 
     let(rand_n = rands(0, 1, 1)[0])
     _join([
         for(c = base) 
         let(v = [for(r = rule) if(r[0] == c) r[1]])
         v == [] ? c : 
-        c_or_v(c, v, rand_n, rule, derived_pr, len(v))
+        c_or_v(c, v, rand_n, rule, rule_pr, len(v))
     ]);
 
-function _derive_p(base, rule, derived_pr, n, i = 0) =
-    i == n ? base : _derive_p(_derive1_p(base, rule, derived_pr), rule, derived_pr, n, i + 1);
+function _derive_p(base, rule, rule_pr, n, i = 0) =
+    i == n ? base : _derive_p(_derive1_p(base, rule, rule_pr), rule, rule_pr, n, i + 1);
 
 function _derive1(base, rule) = _join([
     for(c = base) 
@@ -37,10 +37,10 @@ function _derive1(base, rule) = _join([
 function _derive(base, rule, n, i = 0) =
     i == n ? base : _derive(_derive1(base, rule), rule, n, i + 1);
     
-function _lsystem2_derive(rule, n, derived_pr) =
+function _lsystem2_derive(rule, n, rule_pr) =
     let(base = assoc_lookup(rule, "S"))
-    is_undef(derived_pr) ? _derive(base, rule, n) : 
-    _derive_p(base, rule, derived_pr, n);
+    is_undef(rule_pr) ? _derive(base, rule, n) : 
+    _derive_p(base, rule, rule_pr, n);
 
 function _next_stack(t, code, stack) = 
     code == "[" ? concat([t], stack) :
diff --git a/src/experimental/lsystem2.scad b/src/experimental/lsystem2.scad
index 573fc99b..543ef8fb 100644
--- a/src/experimental/lsystem2.scad
+++ b/src/experimental/lsystem2.scad
@@ -1,9 +1,9 @@
 use <experimental/_impl/_lsystem2_impl.scad>;
 use <turtle/turtle2d.scad>;
 
-function lsystem2(rule, n, angle, leng = 1, heading = 0, start = [0, 0], forward_chars = "F", derived_pr) =
+function lsystem2(rule, n, angle, leng = 1, heading = 0, start = [0, 0], forward_chars = "F", rule_pr) =
     let(
-        derived = _lsystem2_derive(rule, n, derived_pr),
+        derived = _lsystem2_derive(rule, n, rule_pr),
         codes = forward_chars == "F" ? derived : _join([
             for(c = derived)
             let(idx = search(c, forward_chars))