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 2e322f87dac..ec31e760c31 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
@@ -35,7 +35,7 @@
 
 namespace CGAL {
 
-  namespace POLYLINE{
+  namespace polyline{
 
 
     /*! \class
@@ -601,6 +601,6 @@ namespace CGAL {
 
       return (is);
     }
-  }// namespace POLYLINE
+  }// namespace polyline
 } //namespace CGAL
 #endif
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 9ec60770ce7..2b891659011 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
@@ -107,13 +107,13 @@ public:
    * A polyline represents a general continuous piecewise-linear curve, without
    * degenerated segments.
    */
-  typedef POLYLINE::Polyline_2<Segment_traits_2>            Curve_2;
+  typedef polyline::Polyline_2<Segment_traits_2>            Curve_2;
   /*!
    * An x monotone polyline represents a continuous piecewise-linear curve which
    * is either strongly x-monotone or vertical. Again, the polyline is without
    * degenerated segments.
    */
-  typedef POLYLINE::X_monotone_polyline_2<Segment_traits_2> X_monotone_curve_2;
+  typedef polyline::X_monotone_polyline_2<Segment_traits_2> X_monotone_curve_2;
 
   typedef typename Segment_traits_2::Multiplicity       Multiplicity;