diff --git a/core/common.hpp b/core/common.hpp
index e8afc87..c2f833f 100644
--- a/core/common.hpp
+++ b/core/common.hpp
@@ -49,6 +49,8 @@
 #include <ndn-cxx/face.hpp>
 #include <ndn-cxx/interest.hpp>
 #include <ndn-cxx/security/key-chain.hpp>
+#include <ndn-cxx/util/scheduler.hpp>
+#include <ndn-cxx/util/signal.hpp>
 
 namespace ndn {
 
@@ -56,6 +58,9 @@
 
 using boost::noncopyable;
 
+namespace signal = util::signal;
+namespace scheduler = util::scheduler;
+
 
 } // namespace ndn