diff --git a/src/handles/base-handle.hpp b/src/handles/base-handle.hpp
index 95b8caa..a598883 100644
--- a/src/handles/base-handle.hpp
+++ b/src/handles/base-handle.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
- * Copyright (c) 2014,  Regents of the University of California.
+ * Copyright (c) 2014-2017, 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.
@@ -31,7 +31,7 @@
 class BaseHandle : noncopyable
 {
 public:
-  class Error : std::runtime_error
+  class Error : public std::runtime_error
   {
   public:
     explicit