diff --git a/include/magic_enum.hpp b/include/magic_enum.hpp
index 2feb4e9..b6eb00a 100644
--- a/include/magic_enum.hpp
+++ b/include/magic_enum.hpp
@@ -439,7 +439,6 @@ constexpr E operator^(E lhs, E rhs) {
 template <typename E, typename D = detail::enable_if_enum_t<E>>
 constexpr E& operator|=(E& lhs, E rhs) {
   static_assert(detail::check_enum_v<E, D>, "magic_enum::bitwise_operators::operator|= requires enum type.");
-  using U = std::underlying_type_t<D>;
 
   return lhs = lhs | rhs;
 }
@@ -447,7 +446,6 @@ constexpr E& operator|=(E& lhs, E rhs) {
 template <typename E, typename D = detail::enable_if_enum_t<E>>
 constexpr E& operator&=(E& lhs, E rhs) {
   static_assert(detail::check_enum_v<E, D>, "magic_enum::bitwise_operators::operator%= requires enum type.");
-  using U = std::underlying_type_t<D>;
 
   return lhs = lhs & rhs;
 }
@@ -455,7 +453,6 @@ constexpr E& operator&=(E& lhs, E rhs) {
 template <typename E, typename D = detail::enable_if_enum_t<E>>
 constexpr E& operator^=(E& lhs, E rhs) {
   static_assert(detail::check_enum_v<E, D>, "magic_enum::bitwise_operators::operator^= requires enum type.");
-  using U = std::underlying_type_t<D>;
 
   return lhs = lhs ^ rhs;
 }