diff --git a/src/protocol-detail/challenge.cpp b/src/protocol-detail/challenge.cpp
index 2923270..e4d5ecb 100644
--- a/src/protocol-detail/challenge.cpp
+++ b/src/protocol-detail/challenge.cpp
@@ -29,7 +29,7 @@
 CHALLENGE::encodeDataPayload(const CertificateRequest& request)
 {
   Block response = makeEmptyBlock(tlv_encrypted_payload);
-  response.push_back(makeNonNegativeIntegerBlock(tlv_status, request.m_status));
+  response.push_back(makeNonNegativeIntegerBlock(tlv_status, static_cast<size_t>(request.m_status)));
   response.push_back(makeStringBlock(tlv_challenge_status, request.m_challengeStatus));
   response.push_back(makeNonNegativeIntegerBlock(tlv_remaining_tries, request.m_remainingTries));
   response.push_back(makeNonNegativeIntegerBlock(tlv_remaining_time, request.m_remainingTime));
diff --git a/src/protocol-detail/new.cpp b/src/protocol-detail/new.cpp
index 20eaafb..0c33ba8 100644
--- a/src/protocol-detail/new.cpp
+++ b/src/protocol-detail/new.cpp
@@ -63,7 +63,7 @@
   response.push_back(makeStringBlock(tlv_ecdh_pub, ecdhKey));
   response.push_back(makeStringBlock(tlv_salt, salt));
   response.push_back(makeStringBlock(tlv_request_id, request.m_requestId));
-  response.push_back(makeNonNegativeIntegerBlock(tlv_status, request.m_status));
+  response.push_back(makeNonNegativeIntegerBlock(tlv_status, static_cast<size_t>(request.m_status)));
   for (const auto& entry: challenges) {
     response.push_back(makeStringBlock(tlv_challenge, entry));
   }
diff --git a/src/protocol-detail/revoke.cpp b/src/protocol-detail/revoke.cpp
index 5bde720..b31ae55 100644
--- a/src/protocol-detail/revoke.cpp
+++ b/src/protocol-detail/revoke.cpp
@@ -62,7 +62,7 @@
   response.push_back(makeStringBlock(tlv_ecdh_pub, ecdhKey));
   response.push_back(makeStringBlock(tlv_salt, salt));
   response.push_back(makeStringBlock(tlv_request_id, request.m_requestId));
-  response.push_back(makeNonNegativeIntegerBlock(tlv_status, request.m_status));
+  response.push_back(makeNonNegativeIntegerBlock(tlv_status, static_cast<size_t>(request.m_status)));
   for (const auto& entry: challenges) {
     response.push_back(makeStringBlock(tlv_challenge, entry));
   }