diff --git a/src/challenge/challenge-possession.cpp b/src/challenge/challenge-possession.cpp
index 99ece96..73a0c29 100644
--- a/src/challenge/challenge-possession.cpp
+++ b/src/challenge/challenge-possession.cpp
@@ -28,7 +28,7 @@
 namespace ndncert {
 
 NDN_LOG_INIT(ndncert.challenge.possession);
-NDNCERT_REGISTER_CHALLENGE(ChallengePossession, "Possession");
+NDNCERT_REGISTER_CHALLENGE(ChallengePossession, "possession");
 
 const std::string ChallengePossession::PARAMETER_KEY_CREDENTIAL_CERT = "issued-cert";
 const std::string ChallengePossession::PARAMETER_KEY_NONCE = "nonce";
diff --git a/src/detail/ca-profile.cpp b/src/detail/ca-profile.cpp
index 7986830..0f1ad01 100644
--- a/src/detail/ca-profile.cpp
+++ b/src/detail/ca-profile.cpp
@@ -66,7 +66,7 @@
       auto challengeType = item.second.get(CONFIG_CHALLENGE, "");
       challengeType = boost::algorithm::to_lower_copy(challengeType);
       if (challengeType == "") {
-        NDN_THROW(std::runtime_error("Challenge type canont be empty."));
+        NDN_THROW(std::runtime_error("Challenge type cannot be empty."));
       }
       if (!ChallengeModule::isChallengeSupported(challengeType)) {
         NDN_THROW(std::runtime_error("Challenge " + challengeType + " is not supported."));