diff --git a/Visibility_2/include/CGAL/Naive_visibility_2.h b/Visibility_2/include/CGAL/Naive_visibility_2.h
index 6204f43b379..ea9bfd38fa7 100644
--- a/Visibility_2/include/CGAL/Naive_visibility_2.h
+++ b/Visibility_2/include/CGAL/Naive_visibility_2.h
@@ -1,3 +1,23 @@
+// Copyright (c) 2013 Technical University Braunschweig (Germany).
+// All rights reserved.
+//
+// This file is part of CGAL (www.cgal.org).
+// You can redistribute it and/or modify it under the terms of the GNU
+// General Public License as published by the Free Software Foundation,
+// either version 3 of the License, or (at your option) any later version.
+//
+// Licensees holding a valid commercial license may use this file in
+// accordance with the commercial license agreement provided with the software.
+//
+// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
+// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+//
+// $URL$
+// $Id$
+//
+//
+// Author(s):  Kan Huang <huangkandiy@gmail.com>
+//             
 #ifndef CGAL_NAIVE_VISIBILITY_2_H
 #define CGAL_NAIVE_VISIBILITY_2_H
 
diff --git a/Visibility_2/test/test_naive_visibility.cpp b/Visibility_2/test/test_naive_visibility.cpp
index a0c8186bc92..c72055a984c 100644
--- a/Visibility_2/test/test_naive_visibility.cpp
+++ b/Visibility_2/test/test_naive_visibility.cpp
@@ -12,6 +12,7 @@
 #include <CGAL/Naive_visibility_2.h>
 #include <CGAL/test_model_methods.h>
 #include <CGAL/test_utils.h>
+#include <CGAL/Preprocessed_visibility_2.h>