diff --git a/tests/unit/ims/in-memory-storage-fifo.t.cpp b/tests/unit/ims/in-memory-storage-fifo.t.cpp
index bdf86ea..632a566 100644
--- a/tests/unit/ims/in-memory-storage-fifo.t.cpp
+++ b/tests/unit/ims/in-memory-storage-fifo.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).
  *
@@ -23,10 +23,7 @@
 
 #include "tests/test-common.hpp"
 
-namespace ndn {
-namespace tests {
-
-using namespace ndn::tests;
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Ims)
 BOOST_AUTO_TEST_SUITE(TestInMemoryStorageFifo)
@@ -90,5 +87,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestInMemoryStorageFifo
 BOOST_AUTO_TEST_SUITE_END() // Ims
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/ims/in-memory-storage-lfu.t.cpp b/tests/unit/ims/in-memory-storage-lfu.t.cpp
index 17aa9a6..34285dc 100644
--- a/tests/unit/ims/in-memory-storage-lfu.t.cpp
+++ b/tests/unit/ims/in-memory-storage-lfu.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).
  *
@@ -23,10 +23,7 @@
 
 #include "tests/test-common.hpp"
 
-namespace ndn {
-namespace tests {
-
-using namespace ndn::tests;
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Ims)
 BOOST_AUTO_TEST_SUITE(TestInMemoryStorageLfu)
@@ -130,5 +127,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestInMemoryStorageLfu
 BOOST_AUTO_TEST_SUITE_END() // Ims
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/ims/in-memory-storage-lru.t.cpp b/tests/unit/ims/in-memory-storage-lru.t.cpp
index cbf2bab..5a37ca7 100644
--- a/tests/unit/ims/in-memory-storage-lru.t.cpp
+++ b/tests/unit/ims/in-memory-storage-lru.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).
  *
@@ -23,10 +23,7 @@
 
 #include "tests/test-common.hpp"
 
-namespace ndn {
-namespace tests {
-
-using namespace ndn::tests;
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Ims)
 BOOST_AUTO_TEST_SUITE(TestInMemoryStorageLru)
@@ -132,5 +129,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestInMemoryStorageLru
 BOOST_AUTO_TEST_SUITE_END() // Ims
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/ims/in-memory-storage-persistent.t.cpp b/tests/unit/ims/in-memory-storage-persistent.t.cpp
index d0cabf9..33a3afb 100644
--- a/tests/unit/ims/in-memory-storage-persistent.t.cpp
+++ b/tests/unit/ims/in-memory-storage-persistent.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).
  *
@@ -23,10 +23,7 @@
 
 #include "tests/test-common.hpp"
 
-namespace ndn {
-namespace tests {
-
-using namespace ndn::tests;
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Ims)
 BOOST_AUTO_TEST_SUITE(TestInMemoryStoragePersistent)
@@ -78,5 +75,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestInMemoryStoragePersistent
 BOOST_AUTO_TEST_SUITE_END() // Ims
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/ims/in-memory-storage.t.cpp b/tests/unit/ims/in-memory-storage.t.cpp
index 27caa34..ac1c7c2 100644
--- a/tests/unit/ims/in-memory-storage.t.cpp
+++ b/tests/unit/ims/in-memory-storage.t.cpp
@@ -31,10 +31,7 @@
 
 #include <boost/mpl/vector.hpp>
 
-namespace ndn {
-namespace tests {
-
-using namespace ndn::tests;
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Ims)
 BOOST_AUTO_TEST_SUITE(TestInMemoryStorage)
@@ -601,5 +598,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestInMemoryStorage
 BOOST_AUTO_TEST_SUITE_END() // Ims
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests