diff --git a/tools/ping/client/tracer.hpp b/tools/ping/client/tracer.hpp
index b6b4812..c2d375e 100644
--- a/tools/ping/client/tracer.hpp
+++ b/tools/ping/client/tracer.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2015-2021,  Arizona Board of Regents.
+ * Copyright (c) 2015-2022,  Arizona Board of Regents.
  *
  * This file is part of ndn-tools (Named Data Networking Essential Tools).
  * See AUTHORS.md for complete list of ndn-tools authors and contributors.
@@ -27,9 +27,7 @@
 
 #include "ping.hpp"
 
-namespace ndn {
-namespace ping {
-namespace client {
+namespace ndn::ping::client {
 
 /**
  * @brief prints ping responses and timeouts
@@ -80,8 +78,6 @@
   const Options& m_options;
 };
 
-} // namespace client
-} // namespace ping
-} // namespace ndn
+} // namespace ndn::ping::client
 
 #endif // NDN_TOOLS_PING_CLIENT_TRACER_HPP