diff --git a/tools/ndnsec/sign-req.cpp b/tools/ndnsec/sign-req.cpp
index d8d7486..f9f97e9 100644
--- a/tools/ndnsec/sign-req.cpp
+++ b/tools/ndnsec/sign-req.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2019 Regents of the University of California.
+ * Copyright (c) 2013-2020 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -22,6 +22,8 @@
 #include "ndnsec.hpp"
 #include "util.hpp"
 
+#include "ndn-cxx/util/io.hpp"
+
 namespace ndn {
 namespace ndnsec {