diff --git a/utils/ndn-time.hpp b/utils/ndn-time.hpp
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+++ b/utils/ndn-time.hpp
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+/* -*-  Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2012-2014 University of California, Los Angeles
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation;
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifndef NDNSIM_UTILS_TIME_HPP
+#define NDNSIM_UTILS_TIME_HPP
+
+#include "ns3/ndnSIM/model/ndn-common.hpp"
+
+#include <ndn-cxx/util/time-custom-clock.hpp>
+
+namespace ns3 {
+namespace ndn {
+namespace time {
+
+class CustomSystemClock : public CustomClock<system_clock> {
+public:
+  system_clock::time_point
+  getNow() const;
+
+  std::string
+  getSince() const;
+
+  boost::posix_time::time_duration
+  toPosixDuration(const system_clock::duration& duration) const;
+};
+
+class CustomSteadyClock : public CustomClock<steady_clock> {
+public:
+  steady_clock::time_point
+  getNow() const;
+
+  std::string
+  getSince() const;
+
+  boost::posix_time::time_duration
+  toPosixDuration(const steady_clock::duration& duration) const;
+};
+
+} // namespace time
+} // namespace ndn
+} // namespace ns3
+
+#endif // NDNSIM_UTILS_TIME_HPP