diff --git a/tests/key-chain-fixture.hpp b/tests/key-chain-fixture.hpp
index ec1cac3..dc3a444 100644
--- a/tests/key-chain-fixture.hpp
+++ b/tests/key-chain-fixture.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,8 +27,7 @@
 
 #include "tests/test-home-fixture.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 /**
  * @brief A fixture providing an in-memory KeyChain.
@@ -81,7 +80,6 @@
   std::vector<std::string> m_certFiles;
 };
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
 
 #endif // NDN_CXX_TESTS_KEY_CHAIN_FIXTURE_HPP