diff --git a/tests/unit-test-time-fixture.hpp b/tests/unit-test-time-fixture.hpp
index cebce38..c497940 100644
--- a/tests/unit-test-time-fixture.hpp
+++ b/tests/unit-test-time-fixture.hpp
@@ -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) 2013-2021 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -22,10 +22,12 @@
 #ifndef NDN_TESTS_UNIT_UNIT_TEST_TIME_FIXTURE_HPP
 #define NDN_TESTS_UNIT_UNIT_TEST_TIME_FIXTURE_HPP
 
+#include "detail/ndncert-common.hpp"
+
 #include <ndn-cxx/util/time-unit-test-clock.hpp>
+
 #include <boost/asio/io_service.hpp>
 
-namespace ndn {
 namespace ndncert {
 namespace tests {
 
@@ -35,8 +37,8 @@
 {
 public:
   UnitTestTimeFixture()
-    : steadyClock(make_shared<time::UnitTestSteadyClock>())
-    , systemClock(make_shared<time::UnitTestSystemClock>())
+    : steadyClock(std::make_shared<time::UnitTestSteadyClock>())
+    , systemClock(std::make_shared<time::UnitTestSystemClock>())
   {
     time::setCustomClocks(steadyClock, systemClock);
   }
@@ -95,13 +97,12 @@
   }
 
 public:
-  shared_ptr<time::UnitTestSteadyClock> steadyClock;
-  shared_ptr<time::UnitTestSystemClock> systemClock;
+  std::shared_ptr<time::UnitTestSteadyClock> steadyClock;
+  std::shared_ptr<time::UnitTestSystemClock> systemClock;
   boost::asio::io_service io;
 };
 
 } // namespace tests
 } // namespace ndncert
-} // namespace ndn
 
 #endif // NDN_TESTS_UNIT_UNIT_TEST_TIME_FIXTURE_HPP