diff --git a/src/aria2api.cc b/src/aria2api.cc
index 9b08089a..f295a6a1 100644
--- a/src/aria2api.cc
+++ b/src/aria2api.cc
@@ -661,6 +661,29 @@ void pushRequestOption
}
} // namespace
+namespace {
+const std::string& getRequestOption(const SharedHandle