diff --git a/src/challenge-module/challenge-credential.hpp b/src/challenge-module/challenge-credential.hpp
index bf53175..ad2b197 100644
--- a/src/challenge-module/challenge-credential.hpp
+++ b/src/challenge-module/challenge-credential.hpp
@@ -74,7 +74,7 @@
   static const std::string FAILURE_INVALID_FORMAT_CREDENTIAL;
   static const std::string FAILURE_INVALID_FORMAT_SELF_SIGNED;
   static const std::string JSON_CREDENTIAL_CERT;
-  static const std::string JSON_CREDENTIAL_SELF;
+  static const std::string JSON_PROOF_OF_PRIVATE_KEY;
 
 PUBLIC_WITH_TESTS_ELSE_PRIVATE:
   std::list<security::v2::Certificate> m_trustAnchors;