diff --git a/src/face.cpp b/src/face.cpp
index 2f80754..1add5db 100644
--- a/src/face.cpp
+++ b/src/face.cpp
@@ -346,7 +346,7 @@
 }
 
 void
-Face::doProcessEvents(const time::milliseconds& timeout, bool keepThread)
+Face::doProcessEvents(time::milliseconds timeout, bool keepThread)
 {
   if (m_ioService.stopped()) {
     m_ioService.reset(); // ensure that run()/poll() will do some work
diff --git a/src/face.hpp b/src/face.hpp
index 4e722c6..b375e93 100644
--- a/src/face.hpp
+++ b/src/face.hpp
@@ -1,5 +1,5 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/**
+/*
  * Copyright (c) 2013-2017 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
@@ -434,7 +434,7 @@
    * log/disregard all exceptions.
    */
   void
-  processEvents(const time::milliseconds& timeout = time::milliseconds::zero(),
+  processEvents(time::milliseconds timeout = time::milliseconds::zero(),
                 bool keepThread = false)
   {
     this->doProcessEvents(timeout, keepThread);
@@ -469,7 +469,7 @@
 
 protected:
   virtual void
-  doProcessEvents(const time::milliseconds& timeout, bool keepThread);
+  doProcessEvents(time::milliseconds timeout, bool keepThread);
 
 private:
   /**
diff --git a/src/util/dummy-client-face.cpp b/src/util/dummy-client-face.cpp
index 79586c6..24b05a3 100644
--- a/src/util/dummy-client-face.cpp
+++ b/src/util/dummy-client-face.cpp
@@ -1,5 +1,5 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/**
+/*
  * Copyright (c) 2013-2017 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
@@ -265,7 +265,7 @@
 }
 
 void
-DummyClientFace::doProcessEvents(const time::milliseconds& timeout, bool keepThread)
+DummyClientFace::doProcessEvents(time::milliseconds timeout, bool keepThread)
 {
   if (m_processEventsOverride != nullptr) {
     m_processEventsOverride(timeout);
diff --git a/src/util/dummy-client-face.hpp b/src/util/dummy-client-face.hpp
index 630913c..781a797 100644
--- a/src/util/dummy-client-face.hpp
+++ b/src/util/dummy-client-face.hpp
@@ -1,5 +1,5 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/**
+/*
  * Copyright (c) 2013-2017 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
@@ -120,7 +120,7 @@
   enableRegistrationReply();
 
   void
-  doProcessEvents(const time::milliseconds& timeout, bool keepThread) override;
+  doProcessEvents(time::milliseconds timeout, bool keepThread) override;
 
 public:
   /** \brief Interests sent out of this DummyClientFace