diff --git a/daemon/face/protocol-factory.cpp b/daemon/face/protocol-factory.cpp
index 5acb18f..1d70fda 100644
--- a/daemon/face/protocol-factory.cpp
+++ b/daemon/face/protocol-factory.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,
@@ -28,8 +28,7 @@
 #include <boost/range/adaptor/map.hpp>
 #include <boost/range/algorithm/copy.hpp>
 
-namespace nfd {
-namespace face {
+namespace nfd::face {
 
 ProtocolFactory::Registry&
 ProtocolFactory::getRegistry()
@@ -129,5 +128,4 @@
   return {};
 }
 
-} // namespace face
-} // namespace nfd
+} // namespace nfd::face