diff --git a/Boolean_set_operations_2/include/CGAL/General_polygon_set_2.h b/Boolean_set_operations_2/include/CGAL/General_polygon_set_2.h
index 0948eecee70..c61790e7e23 100644
--- a/Boolean_set_operations_2/include/CGAL/General_polygon_set_2.h
+++ b/Boolean_set_operations_2/include/CGAL/General_polygon_set_2.h
@@ -51,7 +51,7 @@ public:
   typedef Dcel_                                           Dcel;
   typedef typename Traits_2::Polygon_2                    Polygon_2;
   typedef typename Traits_2::Polygon_with_holes_2         Polygon_with_holes_2;
-  typedef Arrangement_2<Traits_2, Dcel>                   Arrangement_2;
+  typedef CGAL::Arrangement_2<Traits_2, Dcel>             Arrangement_2;
   typedef std::size_t                                     Size;
 
 private:
diff --git a/Minkowski_sum_2/include/CGAL/Minkowski_sum_2/Approx_offset_base_2.h b/Minkowski_sum_2/include/CGAL/Minkowski_sum_2/Approx_offset_base_2.h
index 95bc8441676..912e9f5075a 100644
--- a/Minkowski_sum_2/include/CGAL/Minkowski_sum_2/Approx_offset_base_2.h
+++ b/Minkowski_sum_2/include/CGAL/Minkowski_sum_2/Approx_offset_base_2.h
@@ -43,7 +43,7 @@ protected:
 
   typedef Kernel                                         Basic_kernel;
   typedef NT                                             Basic_NT;
-  typedef Polygon_2<Kernel, Container_>                  Polygon_2;
+  typedef CGAL::Polygon_2<Kernel, Container_>            Polygon_2;
 
 private:
   
diff --git a/Minkowski_sum_2/include/CGAL/Minkowski_sum_2/Minkowski_sum_conv_2.h b/Minkowski_sum_2/include/CGAL/Minkowski_sum_2/Minkowski_sum_conv_2.h
index 2e9dbf5f884..90bcced93a8 100644
--- a/Minkowski_sum_2/include/CGAL/Minkowski_sum_2/Minkowski_sum_conv_2.h
+++ b/Minkowski_sum_2/include/CGAL/Minkowski_sum_2/Minkowski_sum_conv_2.h
@@ -37,7 +37,7 @@ class Minkowski_sum_by_convolution_2
 public:
 
   typedef Kernel_                                        Kernel;
-  typedef Polygon_2<Kernel, Container_>                  Polygon_2;
+  typedef CGAL::Polygon_2<Kernel, Container_>            Polygon_2;
 
 private:
 
diff --git a/Minkowski_sum_2/include/CGAL/Minkowski_sum_2/Union_of_cycles_2.h b/Minkowski_sum_2/include/CGAL/Minkowski_sum_2/Union_of_cycles_2.h
index ddcff01b27a..bf347d48061 100644
--- a/Minkowski_sum_2/include/CGAL/Minkowski_sum_2/Union_of_cycles_2.h
+++ b/Minkowski_sum_2/include/CGAL/Minkowski_sum_2/Union_of_cycles_2.h
@@ -44,7 +44,7 @@ protected:
 
   // Arrangement-related types:
   typedef Arr_face_extended_dcel<Traits_2, int>          Dcel;
-  typedef Arrangement_2<Traits_2, Dcel>                  Arrangement_2;
+  typedef CGAL::Arrangement_2<Traits_2, Dcel>            Arrangement_2;
   typedef typename Arrangement_2::Vertex_handle          Vertex_handle;
   typedef typename Arrangement_2::Halfedge_handle        Halfedge_handle;
   typedef typename Arrangement_2::Face_handle            Face_handle;