diff --git a/daemon/fw/self-learning-strategy.cpp b/daemon/fw/self-learning-strategy.cpp
index 80630dc..89ca397 100644
--- a/daemon/fw/self-learning-strategy.cpp
+++ b/daemon/fw/self-learning-strategy.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2021,  Regents of the University of California,
+ * Copyright (c) 2014-2022,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -193,7 +193,7 @@
 
   runOnRibIoService([pitEntryWeak = weak_ptr<pit::Entry>{pitEntry}, inFaceId = inFace.getId(), data, this] {
     rib::Service::get().getRibManager().slFindAnn(data.getName(),
-      [pitEntryWeak, inFaceId, data, this] (optional<ndn::PrefixAnnouncement> paOpt) {
+      [pitEntryWeak, inFaceId, data, this] (std::optional<ndn::PrefixAnnouncement> paOpt) {
         if (paOpt) {
           runOnMainIoService([pitEntryWeak, inFaceId, data, pa = std::move(*paOpt), this] {
             auto pitEntry = pitEntryWeak.lock();