diff --git a/include/snipplib/concepts/snplib_concepts.h b/include/snipplib/concepts/snplib_concepts.h
index 617340a..89ab5e0 100644
--- a/include/snipplib/concepts/snplib_concepts.h
+++ b/include/snipplib/concepts/snplib_concepts.h
@@ -185,11 +185,11 @@ concept ret_expected_c = requires {
     }(std::type_identity<std::remove_cvref_t<T>>{});
 };
 
-// template <typename T, typename ValT>
-// concept ret_expected_c = requires {
-//     []<ret_error_c ErrT>(std::type_identity<std::expected<ValT, ErrT>>) {
-//     }(std::type_identity<std::remove_cvref_t<T>>{});
-// };
+template <typename T, typename ValT>
+concept ret_expected_type_c = requires {
+    []<ret_error_c ErrT>(std::type_identity<std::expected<ValT, ErrT>>) {
+    }(std::type_identity<std::remove_cvref_t<T>>{});
+};
 
 
 // result of asynchronous callable