diff --git a/src/challenge-modules/challenge-credential.hpp b/src/challenge-modules/challenge-credential.hpp
index 07b0158..2354767 100644
--- a/src/challenge-modules/challenge-credential.hpp
+++ b/src/challenge-modules/challenge-credential.hpp
@@ -53,7 +53,7 @@
 
   // For CA
   std::tuple<ErrorCode, std::string>
-  handleChallengeRequest(const Block& params, RequestState& request) override;
+  handleChallengeRequest(const Block& params, CaState& request) override;
 
   // For Client
   std::vector<std::tuple<std::string, std::string>>