diff --git a/tools/chunks/catchunks/discover-version-iterative.hpp b/tools/chunks/catchunks/discover-version-iterative.hpp
index e76ff17..8880a6d 100644
--- a/tools/chunks/catchunks/discover-version-iterative.hpp
+++ b/tools/chunks/catchunks/discover-version-iterative.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2016-2017, Regents of the University of California,
+ * Copyright (c) 2016-2019, Regents of the University of California,
  *                          Colorado State University,
  *                          University Pierre & Marie Curie, Sorbonne University.
  *
@@ -95,6 +95,9 @@
   void
   handleTimeout(const Interest& interest, const std::string& reason) final;
 
+  void
+  handleNack(const Interest& interest, const std::string& reason) final;
+
 private:
   uint64_t m_latestVersion;
   shared_ptr<const Data> m_latestVersionData;