diff --git a/daemon/table/name-tree-iterator.cpp b/daemon/table/name-tree-iterator.cpp
index 33b5382..001bb06 100644
--- a/daemon/table/name-tree-iterator.cpp
+++ b/daemon/table/name-tree-iterator.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2019,  Regents of the University of California,
+ * Copyright (c) 2014-2022,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -30,8 +30,7 @@
 #include <boost/range/concepts.hpp>
 #include <ndn-cxx/util/concepts.hpp>
 
-namespace nfd {
-namespace name_tree {
+namespace nfd::name_tree {
 
 NDN_CXX_ASSERT_FORWARD_ITERATOR(Iterator);
 BOOST_CONCEPT_ASSERT((boost::ForwardRangeConcept<Range>));
@@ -257,5 +256,4 @@
   i = Iterator();
 }
 
-} // namespace name_tree
-} // namespace nfd
+} // namespace nfd::name_tree