diff --git a/src/detail/ca-storage.hpp b/src/detail/ca-storage.hpp
index 70a0ac9..b5c2ce7 100644
--- a/src/detail/ca-storage.hpp
+++ b/src/detail/ca-storage.hpp
@@ -33,7 +33,7 @@
    * @throw if request cannot be fetched from underlying data storage
    */
   virtual CaState
-  getRequest(const std::string& requestId) = 0;
+  getRequest(const RequestID& requestId) = 0;
 
   /**
    * @throw if there is an existing request with the same request ID
@@ -45,7 +45,7 @@
   updateRequest(const CaState& request) = 0;
 
   virtual void
-  deleteRequest(const std::string& requestId) = 0;
+  deleteRequest(const RequestID& requestId) = 0;
 
   virtual std::list<CaState>
   listAllRequests() = 0;