diff --git a/src/identity-challenge/challenge-pin.cpp b/src/identity-challenge/challenge-pin.cpp
index fe17cd1..c9f98ba 100644
--- a/src/identity-challenge/challenge-pin.cpp
+++ b/src/identity-challenge/challenge-pin.cpp
@@ -48,7 +48,7 @@
     std::string secretCode = generateSecretCode();
     JsonSection secretJson;
     secretJson.add(PARAMETER_KEY_CODE, secretCode);
-    NDN_LOG_TRACE("Secret for request " << request.m_requestId << " : " << secretCode);
+    NDN_LOG_TRACE("Secret for request " << toHex(request.m_requestId.data(), request.m_requestId.size()) << " : " << secretCode);
     return returnWithNewChallengeStatus(request, NEED_CODE, std::move(secretJson), m_maxAttemptTimes, m_secretLifetime);
   }
   if (request.m_challengeState) {