diff --git a/src/challenge-module/challenge-credential.hpp b/src/challenge-module/challenge-credential.hpp
index 2afe38e..93838a8 100644
--- a/src/challenge-module/challenge-credential.hpp
+++ b/src/challenge-module/challenge-credential.hpp
@@ -52,7 +52,7 @@
   ChallengeCredential(const std::string& configPath = "");
 
   // For CA
-  std::tuple<Error, std::string>
+  std::tuple<ErrorCode, std::string>
   handleChallengeRequest(const Block& params, CertificateRequest& request) override;
 
   // For Client