1 diff --git a/include/fmt/os.h b/include/fmt/os.h
2 index 88151006..11c3b2cc 100644
5 @@ -375,7 +375,7 @@ struct ostream_params {
9 -static constexpr detail::buffer_size buffer_size;
10 +static constexpr detail::buffer_size buffer_size{};
12 // A fast output stream which is not thread-safe.
13 class ostream final : private detail::buffer<char> {