diff --git a/src/detail/pending-interest.hpp b/src/detail/pending-interest.hpp
index 2a4da87..a4f643f 100644
--- a/src/detail/pending-interest.hpp
+++ b/src/detail/pending-interest.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2017 Regents of the University of California.
+ * Copyright (c) 2013-2018 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -22,6 +22,8 @@
 #ifndef NDN_DETAIL_PENDING_INTEREST_HPP
 #define NDN_DETAIL_PENDING_INTEREST_HPP
 
+#include "../face.hpp"
+
 #include "../data.hpp"
 #include "../interest.hpp"
 #include "../lp/nack.hpp"