diff --git a/src/configuration.hpp b/src/configuration.hpp
index 8fc3c74..42d79dd 100644
--- a/src/configuration.hpp
+++ b/src/configuration.hpp
@@ -79,15 +79,17 @@
   parseChallengeList(const JsonSection& configSection);
 };
 
+namespace ca {
+
 /**
  * @brief The function would be invoked whenever the certificate request status is updated.
  * The callback is used to notice the CA application or CA command line tool. The callback is
  * fired whenever a request instance is created, challenge status is updated, and when certificate
  * is issued.
  *
- * @param CaState The state of the certificate request whose status is updated.
+ * @param RequestState The state of the certificate request whose status is updated.
  */
-using StatusUpdateCallback = function<void(const CaState&)>;
+using StatusUpdateCallback = function<void(const RequestState&)>;
 
 /**
  * @brief CA's configuration on NDNCERT.
@@ -138,6 +140,8 @@
   std::vector<std::unique_ptr<NameAssignmentFunc>> m_nameAssignmentFuncs;
 };
 
+} // namespace ca
+
 /**
  * @brief Represents Client configuration
  *