diff --git a/Arrangement_on_surface_2/include/CGAL/Arr_geometry_traits/Polyline_2.h b/Arrangement_on_surface_2/include/CGAL/Arr_geometry_traits/Polyline_2.h
index 6ba2f98c7ec..1cb470b0d46 100644
--- a/Arrangement_on_surface_2/include/CGAL/Arr_geometry_traits/Polyline_2.h
+++ b/Arrangement_on_surface_2/include/CGAL/Arr_geometry_traits/Polyline_2.h
@@ -553,8 +553,16 @@ private:
 
     while (iter != cv.end_segments())
       {
-        os << "  " << *iter;
-        ++iter;
+        if (iter == cv.begin_segments())
+          {
+            os << " " << *iter;
+            ++iter;
+          }
+        else
+          {
+            os << " <-> " << *iter;
+            ++iter;
+          }
       }
     return (os);
   }