diff --git a/example/example_switch.cpp b/example/example_switch.cpp
index 78432b7..c168fcc 100644
--- a/example/example_switch.cpp
+++ b/example/example_switch.cpp
@@ -38,8 +38,8 @@ constexpr std::string_view DoWork<Color::GREEN>() {
 }
 
 // Helper type for the visitor pattern.
-template<class... Ts> struct overloaded : Ts... { using Ts::operator()...; };
-template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;
+template <typename... Ts> struct overloaded : Ts... { using Ts::operator()...; };
+template <typename... Ts> overloaded(Ts...) -> overloaded<Ts...>;
 
 int main() {
   Color c = Color::RED;
diff --git a/include/magic_enum.hpp b/include/magic_enum.hpp
index 84aa863..ea7af86 100644
--- a/include/magic_enum.hpp
+++ b/include/magic_enum.hpp
@@ -705,7 +705,7 @@ constexpr enum_subtype subtype(std::true_type) noexcept {
         return enum_subtype::common;
       }
     }
-    return flags_values.size() > 0;
+    return enum_subtype::flags;
 #else
     return enum_subtype::common;
 #endif
@@ -1106,14 +1106,14 @@ template <typename E>
 }
 
 // Returns number of enum values.
-template <typename E, auto S = detail::subtype_v<E>>
+template <typename E, detail::enum_subtype S = detail::subtype_v<E>>
 [[nodiscard]] constexpr auto enum_count() noexcept -> detail::enable_if_t<E, std::size_t> {
   return detail::count_v<std::decay_t<E>, S>;
 }
 
 // Returns enum value at specified index.
 // No bounds checking is performed: the behavior is undefined if index >= number of enum values.
-template <typename E, auto S = detail::subtype_v<E>>
+template <typename E, detail::enum_subtype S = detail::subtype_v<E>>
 [[nodiscard]] constexpr auto enum_value(std::size_t index) noexcept -> detail::enable_if_t<E, std::decay_t<E>> {
   using D = std::decay_t<E>;
 
@@ -1127,7 +1127,7 @@ template <typename E, auto S = detail::subtype_v<E>>
 }
 
 // Returns enum value at specified index.
-template <typename E, std::size_t I, auto S = detail::subtype_v<E>>
+template <typename E, std::size_t I, detail::enum_subtype S = detail::subtype_v<E>>
 [[nodiscard]] constexpr auto enum_value() noexcept -> detail::enable_if_t<E, std::decay_t<E>> {
   using D = std::decay_t<E>;
   static_assert(I < detail::count_v<D, S>, "magic_enum::enum_value out of range.");
@@ -1136,7 +1136,7 @@ template <typename E, std::size_t I, auto S = detail::subtype_v<E>>
 }
 
 // Returns std::array with enum values, sorted by enum value.
-template <typename E, auto S = detail::subtype_v<E>>
+template <typename E, detail::enum_subtype S = detail::subtype_v<E>>
 [[nodiscard]] constexpr auto enum_values() noexcept -> detail::enable_if_t<E, detail::values_t<E, S>> {
   return detail::values_v<std::decay_t<E>, S>;
 }
@@ -1155,7 +1155,7 @@ template <typename E>
 
 // Obtains index in enum values from enum value.
 // Returns optional with index.
-template <typename E, auto S = detail::subtype_v<E>>
+template <typename E, detail::enum_subtype S = detail::subtype_v<E>>
 [[nodiscard]] constexpr auto enum_index(E value) noexcept -> detail::enable_if_t<E, optional<std::size_t>> {
   using D = std::decay_t<E>;
   using U = underlying_type_t<D>;
@@ -1196,7 +1196,7 @@ template <detail::enum_subtype S, typename E>
 }
 
 // Obtains index in enum values from static storage enum variable.
-template <auto V, auto S = detail::subtype_v<std::decay_t<decltype(V)>>>
+template <auto V, detail::enum_subtype S = detail::subtype_v<std::decay_t<decltype(V)>>>
 [[nodiscard]] constexpr auto enum_index() noexcept -> detail::enable_if_t<decltype(V), std::size_t> {
   constexpr auto index = enum_index<std::decay_t<decltype(V)>, S>(V);
   static_assert(index, "magic_enum::enum_index enum value does not have a index.");
@@ -1216,7 +1216,7 @@ template <auto V>
 
 // Returns name from enum value.
 // If enum value does not have name or value out of range, returns empty string.
-template <typename E, auto S = detail::subtype_v<E>>
+template <typename E, detail::enum_subtype S = detail::subtype_v<E>>
 [[nodiscard]] constexpr auto enum_name(E value) noexcept -> detail::enable_if_t<E, string_view> {
   using D = std::decay_t<E>;
 
@@ -1263,13 +1263,13 @@ template <typename E>
 }
 
 // Returns std::array with names, sorted by enum value.
-template <typename E, auto S = detail::subtype_v<E>>
+template <typename E, detail::enum_subtype S = detail::subtype_v<E>>
 [[nodiscard]] constexpr auto enum_names() noexcept -> detail::enable_if_t<E, detail::names_t<E, S>> {
   return detail::names_v<std::decay_t<E>, S>;
 }
 
 // Returns std::array with pairs (value, name), sorted by enum value.
-template <typename E, auto S = detail::subtype_v<E>>
+template <typename E, detail::enum_subtype S = detail::subtype_v<E>>
 [[nodiscard]] constexpr auto enum_entries() noexcept -> detail::enable_if_t<E, detail::entries_t<E, S>> {
   return detail::entries_v<std::decay_t<E>, S>;
 }
@@ -1279,7 +1279,7 @@ inline constexpr auto case_insensitive = detail::case_insensitive<>{};
 
 // Obtains enum value from integer value.
 // Returns optional with enum value.
-template <typename E, auto S = detail::subtype_v<E>>
+template <typename E, detail::enum_subtype S = detail::subtype_v<E>>
 [[nodiscard]] constexpr auto enum_cast(underlying_type_t<E> value) noexcept -> detail::enable_if_t<E, optional<std::decay_t<E>>> {
   using D = std::decay_t<E>;
 
@@ -1347,7 +1347,7 @@ template <typename E>
 
 // Obtains enum value from name.
 // Returns optional with enum value.
-template <typename E, auto S = detail::subtype_v<E>, typename BinaryPredicate = std::equal_to<>>
+template <typename E, detail::enum_subtype S = detail::subtype_v<E>, typename BinaryPredicate = std::equal_to<>>
 [[nodiscard]] constexpr auto enum_cast(string_view value, [[maybe_unused]] BinaryPredicate p = {}) noexcept(detail::is_nothrow_invocable<BinaryPredicate>()) -> detail::enable_if_t<E, optional<std::decay_t<E>>, BinaryPredicate> {
   using D = std::decay_t<E>;
 
@@ -1414,7 +1414,7 @@ template <typename E, typename BinaryPredicate = std::equal_to<>>
 }
 
 // Checks whether enum contains value with such value.
-template <typename E, auto S = detail::subtype_v<E>>
+template <typename E, detail::enum_subtype S = detail::subtype_v<E>>
 [[nodiscard]] constexpr auto enum_contains(E value) noexcept -> detail::enable_if_t<E, bool> {
   using D = std::decay_t<E>;
   using U = underlying_type_t<D>;
@@ -1441,7 +1441,7 @@ template <typename E>
 }
 
 // Checks whether enum contains value with such integer value.
-template <typename E, auto S = detail::subtype_v<E>>
+template <typename E, detail::enum_subtype S = detail::subtype_v<E>>
 [[nodiscard]] constexpr auto enum_contains(underlying_type_t<E> value) noexcept -> detail::enable_if_t<E, bool> {
   using D = std::decay_t<E>;
 
@@ -1457,7 +1457,7 @@ template <typename E>
 }
 
 // Checks whether enum contains enumerator with such name.
-template <typename E, auto S = detail::subtype_v<E>, typename BinaryPredicate = std::equal_to<>>
+template <typename E, detail::enum_subtype S = detail::subtype_v<E>, typename BinaryPredicate = std::equal_to<>>
 [[nodiscard]] constexpr auto enum_contains(string_view value, BinaryPredicate p = {}) noexcept(detail::is_nothrow_invocable<BinaryPredicate>()) -> detail::enable_if_t<E, bool, BinaryPredicate> {
   using D = std::decay_t<E>;
 
@@ -1472,7 +1472,7 @@ template <typename E, typename BinaryPredicate = std::equal_to<>>
   return static_cast<bool>(enum_flags_cast<D>(value, std::move(p)));
 }
 
-template <typename E, auto S = detail::subtype_v<E>, typename F, detail::enable_if_t<E, int> = 0>
+template <typename E, detail::enum_subtype S = detail::subtype_v<E>, typename F, detail::enable_if_t<E, int> = 0>
 constexpr auto enum_for_each(F&& f) {
   using D = std::decay_t<E>;
   static_assert(std::is_enum_v<D>, "magic_enum::enum_for_each requires enum type.");
diff --git a/include/magic_enum_switch.hpp b/include/magic_enum_switch.hpp
index 385eb25..4e06e46 100644
--- a/include/magic_enum_switch.hpp
+++ b/include/magic_enum_switch.hpp
@@ -142,7 +142,7 @@ constexpr decltype(auto) constexpr_switch(F&& f, E value, Def&& def) {
 
 } // namespace magic_enum::detail
 
-template <typename Result = detail::default_result_type, typename E, auto S = detail::subtype_v<E>, typename F, typename R = detail::result_t<E, S, Result, F>>
+template <typename Result = detail::default_result_type, typename E, detail::enum_subtype S = detail::subtype_v<E>, typename F, typename R = detail::result_t<E, S, Result, F>>
 constexpr decltype(auto) enum_switch(F&& f, E value) {
   using D = std::decay_t<E>;
   static_assert(std::is_enum_v<D>, "magic_enum::enum_switch requires enum type.");
@@ -165,7 +165,7 @@ constexpr decltype(auto) enum_switch(F&& f, E value) {
   return enum_switch<Result, E, S>(std::forward<F>(f), value);
 }
 
-template <typename Result, typename E, auto S = detail::subtype_v<E>, typename F, typename R = detail::result_t<E, S, Result, F>>
+template <typename Result, typename E, detail::enum_subtype S = detail::subtype_v<E>, typename F, typename R = detail::result_t<E, S, Result, F>>
 constexpr decltype(auto) enum_switch(F&& f, E value, Result&& result) {
   using D = std::decay_t<E>;
   static_assert(std::is_enum_v<D>, "magic_enum::enum_switch requires enum type.");