diff --git a/util.hpp b/util.hpp
index 35d2e78..680e2ce 100644
--- a/util.hpp
+++ b/util.hpp
@@ -110,7 +110,7 @@ inline constexpr auto make_offset_index_sequence()
 }
 
 template <typename Fn, size_t... Ints>
-auto for_constexpr(Fn &&func, index_sequence<Ints...>)
+constexpr auto for_constexpr(Fn &&func, index_sequence<Ints...>)
 {
 	if constexpr (util::is_void_v<util::invoke_result_t<Fn, util::integral_constant<size_t, 0>>>) {
 		(func(util::integral_constant<size_t, Ints>{}), ...);