diff --git a/util.cpp b/util.cpp
index 41ff2288..dcf0e1be 100644
--- a/util.cpp
+++ b/util.cpp
@@ -217,6 +217,13 @@ cld exp_parser::parse(int prio) {
     force_eat(")");
     return edge_of_triangle_with_angles(2*M_PI/real(a), M_PI/real(b), M_PI/real(b));
     }
+  else if(eat("regradius(")) {
+    cld a = rparse(0);
+    force_eat(",");
+    cld b = rparse(0);
+    force_eat(")");
+    return edge_of_triangle_with_angles(M_PI/2, M_PI/real(b), M_PI/real(b));
+    }
   else if(eat("ifp(")) {
     cld cond = parse(0);
     force_eat(",");