tests: face system benchmark

Change-Id: Ia2d9125486c57f949e5c855ae6b8d95ffd5aa6e3
Refs: #3567
diff --git a/core/extended-error-message.hpp b/core/extended-error-message.hpp
index 10e62e2..f1443bd 100644
--- a/core/extended-error-message.hpp
+++ b/core/extended-error-message.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
- * Copyright (c) 2014-2015,  Regents of the University of California,
+ * Copyright (c) 2014-2016,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -27,6 +27,7 @@
 #define NFD_CORE_EXTENDED_ERROR_MESSAGE_HPP
 
 #include <boost/exception/get_error_info.hpp>
+#include <sstream>
 
 namespace nfd {