Fix compilation against the latest version of ndn-cxx
Change-Id: I7fc1204f50241ec5f972578c3ea69782cd5f311f
diff --git a/tools/ndncert-client.cpp b/tools/ndncert-client.cpp
index 86ff60f..7f082d8 100644
--- a/tools/ndncert-client.cpp
+++ b/tools/ndncert-client.cpp
@@ -22,6 +22,8 @@
#include "challenge-module.hpp"
#include "logging.hpp"
+#include <iostream>
+
#include <boost/program_options/options_description.hpp>
#include <boost/program_options/variables_map.hpp>
#include <boost/program_options/parsers.hpp>