diff --git a/src/identity-challenge/challenge-credential.cpp b/src/identity-challenge/challenge-credential.cpp
index 0d171e4..e8cedf6 100644
--- a/src/identity-challenge/challenge-credential.cpp
+++ b/src/identity-challenge/challenge-credential.cpp
@@ -191,5 +191,5 @@
   return;
 }
 
-}  // namespace ndncert
-}  // namespace ndn
+} // namespace ndncert
+} // namespace ndn
diff --git a/src/identity-challenge/challenge-email.cpp b/src/identity-challenge/challenge-email.cpp
index a439807..4e2e249 100644
--- a/src/identity-challenge/challenge-email.cpp
+++ b/src/identity-challenge/challenge-email.cpp
@@ -170,5 +170,5 @@
   return;
 }
 
-}  // namespace ndncert
-}  // namespace ndn
+} // namespace ndncert
+} // namespace ndn
diff --git a/src/identity-challenge/challenge-module.hpp b/src/identity-challenge/challenge-module.hpp
index deed763..0f0d0b8 100644
--- a/src/identity-challenge/challenge-module.hpp
+++ b/src/identity-challenge/challenge-module.hpp
@@ -98,7 +98,7 @@
     }                                                                 \
   } g_NdnCert##C##ChallengeRegistrationVariable
 
-}  // namespace ndncert
-}  // namespace ndn
+} // namespace ndncert
+} // namespace ndn
 
-#endif  // NDNCERT_CHALLENGE_MODULE_HPP
+#endif // NDNCERT_CHALLENGE_MODULE_HPP
diff --git a/src/identity-challenge/challenge-pin.cpp b/src/identity-challenge/challenge-pin.cpp
index 8886b67..cd2c03e 100644
--- a/src/identity-challenge/challenge-pin.cpp
+++ b/src/identity-challenge/challenge-pin.cpp
@@ -124,5 +124,5 @@
   request.encode();
   return request;
 }
-}  // namespace ndncert
-}  // namespace ndn
+} // namespace ndncert
+} // namespace ndn