diff --git a/src/detail/challenge-encoder.hpp b/src/detail/challenge-encoder.hpp
index 5c502d2..2329928 100644
--- a/src/detail/challenge-encoder.hpp
+++ b/src/detail/challenge-encoder.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2017-2022, Regents of the University of California.
+ * Copyright (c) 2017-2024, Regents of the University of California.
  *
  * This file is part of ndncert, a certificate management system based on NDN.
  *
@@ -27,7 +27,8 @@
 namespace ndncert::challengetlv {
 
 Block
-encodeDataContent(ca::RequestState& request, const Name& issuedCertName = Name());
+encodeDataContent(ca::RequestState& request, const Name& issuedCertName = Name(),
+                  const Name& forwardingHint = Name());
 
 void
 decodeDataContent(const Block& contentBlock, requester::Request& state);