diff --git a/contrib/epee/include/epee/serialization/keyvalue_serialization_overloads.h b/contrib/epee/include/epee/serialization/keyvalue_serialization_overloads.h
index 044fe1587..2278c3cee 100644
--- a/contrib/epee/include/epee/serialization/keyvalue_serialization_overloads.h
+++ b/contrib/epee/include/epee/serialization/keyvalue_serialization_overloads.h
@@ -33,6 +33,7 @@
 #include <vector>
 #include <deque>
 #include <array>
+#include <optional>
 #include "../span.h"
 #include "../storages/portable_storage_base.h"