diff --git a/src/identity-challenge/challenge-credential.hpp b/src/identity-challenge/challenge-credential.hpp
index 49670f6..0a80a17 100644
--- a/src/identity-challenge/challenge-credential.hpp
+++ b/src/identity-challenge/challenge-credential.hpp
@@ -65,7 +65,7 @@
 
   static void
   fulfillParameters(std::vector<std::tuple<std::string, std::string>>& params,
-                    KeyChain& keyChain, const Name& issuedCertName, const std::string& requestId);
+                    KeyChain& keyChain, const Name& issuedCertName, const RequestID& requestId);
 
   // challenge parameters
   static const std::string PARAMETER_KEY_CREDENTIAL_CERT;