diff --git a/src/detail/ca-profile.hpp b/src/detail/ca-profile.hpp
index 620f49b..6ca9b19 100644
--- a/src/detail/ca-profile.hpp
+++ b/src/detail/ca-profile.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2017-2022, Regents of the University of California.
+ * Copyright (c) 2017-2024, Regents of the University of California.
  *
  * This file is part of ndncert, a certificate management system based on NDN.
  *
@@ -23,6 +23,8 @@
 
 #include "detail/ndncert-common.hpp"
 
+#include <optional>
+
 namespace ndncert {
 
 // used in parsing CA configuration file and Client CA profile storage file
@@ -44,8 +46,8 @@
 {
 public:
   /**
-   * Parse the configuration json.
-   * @param configJson the configuration json to parse
+   * Parse the configuration JSON.
+   * @param json the configuration json to parse
    * @return the CaProfile according to this json
    */
   static CaProfile