diff --git a/src/fios.cpp b/src/fios.cpp
index 2dc788b768..26024efd07 100644
--- a/src/fios.cpp
+++ b/src/fios.cpp
@@ -753,7 +753,7 @@ void ScanScenarios()
 */
 FiosNumberedSaveName::FiosNumberedSaveName(const std::string &prefix) : prefix(prefix), number(-1)
 {
-	static std::optional<std::string> _autosave_path;
+	static opt::optional<std::string> _autosave_path;
 	if (!_autosave_path) _autosave_path = FioFindDirectory(AUTOSAVE_DIR);
 
 	static std::string _prefix; ///< Static as the lambda needs access to it.
diff --git a/src/saveload/upstream/saveload.h b/src/saveload/upstream/saveload.h
index 0e5219a5fd..1b579c7dad 100644
--- a/src/saveload/upstream/saveload.h
+++ b/src/saveload/upstream/saveload.h
@@ -88,7 +88,7 @@ using SaveLoadCompatTable = span<const struct SaveLoadCompat>;
 /** Handler for saving/loading an object to/from disk. */
 class SaveLoadHandler {
 public:
-	std::optional<std::vector<SaveLoad>> load_description;
+	opt::optional<std::vector<SaveLoad>> load_description;
 
 	virtual ~SaveLoadHandler() {}