diff --git a/src/controller.cpp b/src/controller.cpp
index 4d80604..171dfc7 100644
--- a/src/controller.cpp
+++ b/src/controller.cpp
@@ -39,6 +39,8 @@
 
 namespace chronos {
 
+using ndn::shared_ptr;
+
 static const uint8_t ROUTING_PREFIX_SEPARATOR[2] = {0xF0, 0x2E};
 
 // constructor & destructor