diff --git a/tests/unit/security/interest-signer.t.cpp b/tests/unit/security/interest-signer.t.cpp
index b4a3991..b44546b 100644
--- a/tests/unit/security/interest-signer.t.cpp
+++ b/tests/unit/security/interest-signer.t.cpp
@@ -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).
  *
@@ -25,11 +25,10 @@
 #include "tests/key-chain-fixture.hpp"
 #include "tests/unit/clock-fixture.hpp"
 
-namespace ndn {
-namespace security {
-namespace tests {
+namespace ndn::tests {
 
-using namespace ndn::tests;
+using ndn::security::InterestSigner;
+using ndn::security::SigningInfo;
 
 class InterestSignerFixture : public ClockFixture, public KeyChainFixture
 {
@@ -123,6 +122,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestInterestSigner
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests