diff --git a/ndnboost/mpl/list/aux_/O1_size.hpp b/ndnboost/mpl/list/aux_/O1_size.hpp
new file mode 100644
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+++ b/ndnboost/mpl/list/aux_/O1_size.hpp
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+
+#ifndef BOOST_MPL_LIST_AUX_O1_SIZE_HPP_INCLUDED
+#define BOOST_MPL_LIST_AUX_O1_SIZE_HPP_INCLUDED
+
+// Copyright Aleksey Gurtovoy 2000-2004
+//
+// Distributed under the Boost Software License, Version 1.0. 
+// (See accompanying file LICENSE_1_0.txt or copy at 
+// http://www.boost.org/LICENSE_1_0.txt)
+//
+// See http://www.boost.org/libs/mpl for documentation.
+
+// $Id: O1_size.hpp 49267 2008-10-11 06:19:02Z agurtovoy $
+// $Date: 2008-10-10 23:19:02 -0700 (Fri, 10 Oct 2008) $
+// $Revision: 49267 $
+
+#include <ndnboost/mpl/O1_size_fwd.hpp>
+#include <ndnboost/mpl/list/aux_/tag.hpp>
+
+namespace ndnboost { namespace mpl {
+
+template<>
+struct O1_size_impl< aux::list_tag >
+{
+    template< typename List > struct apply
+        : List::size
+    {
+    };
+};
+
+}}
+
+#endif // BOOST_MPL_LIST_AUX_O1_SIZE_HPP_INCLUDED