diff --git a/src/storage/repo-storage.hpp b/src/storage/repo-storage.hpp
index 62d8fa4..597daa8 100644
--- a/src/storage/repo-storage.hpp
+++ b/src/storage/repo-storage.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2022, Regents of the University of California.
+ * Copyright (c) 2014-2023, Regents of the University of California.
  *
  * This file is part of NDN repo-ng (Next generation of NDN repository).
  * See AUTHORS.md for complete list of repo-ng authors and contributors.
@@ -84,8 +84,8 @@
   readData(const Interest& interest) const;
 
 public:
-  ndn::util::Signal<RepoStorage, ndn::Name> afterDataInsertion;
-  ndn::util::Signal<RepoStorage, ndn::Name> afterDataDeletion;
+  ndn::signal::Signal<RepoStorage, ndn::Name> afterDataInsertion;
+  ndn::signal::Signal<RepoStorage, ndn::Name> afterDataDeletion;
 
 private:
   Storage& m_storage;