diff --git a/Arrangement_on_surface_2/include/CGAL/Arr_polyline_traits_2.h b/Arrangement_on_surface_2/include/CGAL/Arr_polyline_traits_2.h
index 949e53cdc17..17c35ae9493 100644
--- a/Arrangement_on_surface_2/include/CGAL/Arr_polyline_traits_2.h
+++ b/Arrangement_on_surface_2/include/CGAL/Arr_polyline_traits_2.h
@@ -210,7 +210,7 @@ namespace CGAL {
        * \pre p2 does not lie on the boundary.
        */
       Comparison_result operator()(const Point_2& p1, const Point_2& p2) const
-      { m_poly_traits.segment_traits_2()->compare_x_2_object()(p1, p2); }
+      { return m_poly_traits.segment_traits_2()->compare_x_2_object()(p1, p2); }
 
       /*! Compare two ends of x-monotone curves in x.
        * \param xs1 the first curve.