diff --git a/examples/ndn-tree-with-l2tracer.cpp b/examples/ndn-tree-with-l2tracer.cpp
index cc24c23..52b8e8d 100644
--- a/examples/ndn-tree-with-l2tracer.cpp
+++ b/examples/ndn-tree-with-l2tracer.cpp
@@ -1,4 +1,23 @@
-// ndn-simple-withl2tracer.cc
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2011-2015  Regents of the University of California.
+ *
+ * This file is part of ndnSIM. See AUTHORS for complete list of ndnSIM authors and
+ * contributors.
+ *
+ * ndnSIM is free software: 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.
+ *
+ * ndnSIM 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
+ * ndnSIM, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ **/
+
+// ndn-simple-withl2tracer.cpp
 
 #include "ns3/core-module.h"
 #include "ns3/network-module.h"