diff --git a/experimental/Intersection/QuadraticUtilities.h b/experimental/Intersection/QuadraticUtilities.h
index 74ab809..fe6bc68 100644
--- a/experimental/Intersection/QuadraticUtilities.h
+++ b/experimental/Intersection/QuadraticUtilities.h
@@ -36,6 +36,7 @@
 int quadraticRootsReal(double A, double B, double C, double t[2]);
 int quadraticRootsValidT(const double A, const double B, const double C, double s[2]);
 void sub_divide(const Quadratic& src, double t1, double t2, Quadratic& dst);
+_Point sub_divide(const Quadratic& src, const _Point& a, const _Point& c, double t1, double t2);
 void toCubic(const Quadratic& , Cubic& );
 _Point top(const Quadratic& , double startT, double endT);
 void xy_at_t(const Quadratic& , double t, double& x, double& y);