diff --git a/tests/unit/encoding/nfd-constants.t.cpp b/tests/unit/encoding/nfd-constants.t.cpp
index e1bc111..6821c44 100644
--- a/tests/unit/encoding/nfd-constants.t.cpp
+++ b/tests/unit/encoding/nfd-constants.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 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).
  *
@@ -27,9 +27,9 @@
 #include <iomanip>
 #include <sstream>
 
-namespace ndn {
-namespace nfd {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::nfd;
 
 BOOST_AUTO_TEST_SUITE(Encoding)
 BOOST_AUTO_TEST_SUITE(TestNfdConstants)
@@ -142,6 +142,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestNfdConstants
 BOOST_AUTO_TEST_SUITE_END() // Encoding
 
-} // namespace tests
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::tests