diff --git a/src/detail/challenge-encoder.hpp b/src/detail/challenge-encoder.hpp
index d0ad429..3eaf4c4 100644
--- a/src/detail/challenge-encoder.hpp
+++ b/src/detail/challenge-encoder.hpp
@@ -18,8 +18,8 @@
  * See AUTHORS.md for complete list of ndncert authors and contributors.
  */
 
-#ifndef NDNCERT_DETAIL_CHALLENGE_STEP_HPP
-#define NDNCERT_DETAIL_CHALLENGE_STEP_HPP
+#ifndef NDNCERT_DETAIL_CHALLENGE_ENCODER_HPP
+#define NDNCERT_DETAIL_CHALLENGE_ENCODER_HPP
 
 #include "detail/ca-request-state.hpp"
 #include "requester-state.hpp"
@@ -40,4 +40,4 @@
 } // namespace ndncert
 } // namespace ndn
 
-#endif // NDNCERT_DETAIL_CHALLENGE_STEP_HPP
\ No newline at end of file
+#endif // NDNCERT_DETAIL_CHALLENGE_ENCODER_HPP
\ No newline at end of file