diff --git a/doc/limitations.md b/doc/limitations.md
index cc1f8a3..cdd3747 100644
--- a/doc/limitations.md
+++ b/doc/limitations.md
@@ -50,7 +50,7 @@
     Banana = 3,
     COUNT = 4
   };
-  // magic_enum::enum_cast<ShapeKind>("Box") -> std::nullopt
+  // magic_enum::enum_cast<ShapeKind>("Box") -> nullopt
   // magic_enum::enum_name(ShapeKind::Box) -> "ConvexBegin"
   ```
 
@@ -76,7 +76,7 @@
   // magic_enum::enum_name(ShapeKind::Box) -> "Box"
 
   // Non-reflected aliases.
-  // magic_enum::enum_cast<ShapeKind>("ConvexBegin") -> std::nullopt
+  // magic_enum::enum_cast<ShapeKind>("ConvexBegin") -> nullopt
   // magic_enum::enum_name(ShapeKind::ConvexBegin) -> "Box"
   ```
 
@@ -87,9 +87,9 @@
     one = 1,
     ONE = 1
   };
-  // magic_enum::enum_cast<Number>("one") -> std::nullopt
+  // magic_enum::enum_cast<Number>("one") -> nullopt
   // magic_enum::enum_name(Number::one) -> ""
-  // magic_enum::enum_cast<Number>("ONE") -> std::nullopt
+  // magic_enum::enum_cast<Number>("ONE") -> nullopt
   // magic_enum::enum_name(Number::ONE) -> ""
   ```
 
diff --git a/doc/reference.md b/doc/reference.md
index 944014b..7d1d670 100644
--- a/doc/reference.md
+++ b/doc/reference.md
@@ -13,7 +13,7 @@
 * [`enum_type_name` returns type name of enum.](#enum_type_name)
 * [`is_unscoped_enum` checks whether type is an Unscoped enumeration.](#is_unscoped_enum)
 * [`is_scoped_enum` checks whether type is an Scoped enumeration.](#is_scoped_enum)
-* [`underlying_type` improved UB-free "SFINAE-friendly" std::underlying_type.](#underlying_type)
+* [`underlying_type` improved UB-free "SFINAE-friendly" underlying_type.](#underlying_type)
 * [`ostream_operators` ostream operators for enums.](#ostream_operators)
 * [`bitwise_operators` bitwise operators for enums.](#bitwise_operators)
 
@@ -41,9 +41,9 @@ constexpr optional<E> enum_cast(string_view value, BinaryPredicate p) noexcept(i
 
 * Obtains enum value from string or integer.
 
-* Returns `std::optional<E>`, using `has_value()` to check contains enum value and `value()` to get the enum value.
+* Returns `optional<E>`, using `has_value()` to check contains enum value and `value()` to get the enum value.
 
-* If argument does not enum value, returns empty `std::optional`.
+* If argument does not enum value, returns empty `optional`.
 
 * Examples
 
@@ -93,7 +93,7 @@ template <typename E>
 constexpr array<E, N> enum_values() noexcept;
 ```
 
-* Returns `std::array<E, N>` with all enum values where `N = number of enum values`, sorted by enum value.
+* Returns `array<E, N>` with all enum values where `N = number of enum values`, sorted by enum value.
 
 * Examples
 
@@ -146,7 +146,7 @@ template <auto V>
 constexpr string_view enum_name() noexcept;
 ```
 
-* Returns name from enum value as `std::string_view` with null-terminated string.
+* Returns name from enum value as `string_view` with null-terminated string.
   * If enum value does not have name or [out of range](limitations.md), `enum_name(value)` returns empty string.
   * If enum value does not have name, `enum_name<value>()` occurs the compilation error `"Enum value does not have a name."`.
 
@@ -177,7 +177,7 @@ template <typename E>
 constexpr array<string_view, N> enum_names() noexcept;
 ```
 
-* Returns `std::array<std::string_view, N>` with all names where `N = number of enum values`, sorted by enum value.
+* Returns `array<string_view, N>` with all names where `N = number of enum values`, sorted by enum value.
 
 * Examples
 
@@ -194,7 +194,7 @@ template <typename E>
 constexpr array<pair<E, string_view>, N> enum_entries() noexcept;
 ```
 
-* Returns `std::array<std::pair<E, std::string_view>, N>` with all pairs (value, name) where `N = number of enum values`, sorted by enum value.
+* Returns `array<pair<E, string_view>, N>` with all pairs (value, name) where `N = number of enum values`, sorted by enum value.
 
 * Examples
 
@@ -214,7 +214,7 @@ constexpr optional<size_t> enum_index() noexcept;
 
 * Obtains index in enum values from enum value.
 
-* Returns `std::optional<std::size_t>` with index.
+* Returns `optional<size_t>` with index.
 
 * Examples
 
@@ -261,7 +261,7 @@ template <typename E>
 constexpr string_view enum_type_name() noexcept;
 ```
 
-* Returns type name of enum as `std::string_view` null-terminated string.
+* Returns type name of enum as `string_view` null-terminated string.
 
 * Examples
 
@@ -331,7 +331,7 @@ template <typename T>
 using underlying_type_t = typename underlying_type<T>::type;
 ```
 
-* Improved UB-free "SFINAE-friendly" [std::underlying_type](https://en.cppreference.com/w/cpp/types/underlying_type).
+* Improved UB-free "SFINAE-friendly" [underlying_type](https://en.cppreference.com/w/cpp/types/underlying_type).
 
 * If T is a complete enumeration type, provides a member typedef type that names the underlying type of T.</br>
   Otherwise, if T is not an enumeration type, there is no member type.</br>
diff --git a/include/magic_enum.hpp b/include/magic_enum.hpp
index 619eda4..5a5f4b2 100644
--- a/include/magic_enum.hpp
+++ b/include/magic_enum.hpp
@@ -154,13 +154,20 @@ struct supported
     : std::false_type {};
 #endif
 
+struct char_equal_to {
+  constexpr bool operator()(char lhs, char rhs) const noexcept {
+    return lhs == rhs;
+  }
+};
+
 template <std::size_t N>
-struct static_string {
+class static_string {
+ public:
   constexpr explicit static_string(string_view str) noexcept : static_string{str, std::make_index_sequence<N>{}} {
     assert(str.size() == N);
   }
 
-  constexpr const char* data() const noexcept { return chars.data(); }
+  constexpr const char* data() const noexcept { return chars_.data(); }
 
   constexpr std::size_t size() const noexcept { return N; }
 
@@ -168,13 +175,14 @@ struct static_string {
 
  private:
   template <std::size_t... I>
-  constexpr static_string(string_view str, std::index_sequence<I...>) noexcept : chars{{str[I]..., '\0'}} {}
+  constexpr static_string(string_view str, std::index_sequence<I...>) noexcept : chars_{{str[I]..., '\0'}} {}
 
-  const std::array<char, N + 1> chars;
+  const std::array<char, N + 1> chars_;
 };
 
 template <>
-struct static_string<0> {
+class static_string<0> {
+ public:
   constexpr explicit static_string(string_view) noexcept {}
 
   constexpr const char* data() const noexcept { return nullptr; }
@@ -184,12 +192,6 @@ struct static_string<0> {
   constexpr operator string_view() const noexcept { return {}; }
 };
 
-struct char_equal_to {
-  constexpr bool operator()(char lhs, char rhs) const noexcept {
-    return lhs == rhs;
-  }
-};
-
 constexpr string_view pretty_name(string_view name) noexcept {
   for (std::size_t i = name.size(); i > 0; --i) {
     if (!((name[i - 1] >= '0' && name[i - 1] <= '9') ||