diff --git a/docs/type_traits.adoc b/docs/type_traits.adoc
index b0bae5f..7724bcf 100644
--- a/docs/type_traits.adoc
+++ b/docs/type_traits.adoc
@@ -7,9 +7,7 @@ contains a few things from the standard:
 * https://en.cppreference.com/w/cpp/types/conditional[`conditional_t`]
   (implemented with fewer template instantiations than a typical standard
   implementation)
-* https://en.cppreference.com/w/cpp/types/is_constant_evaluated[`is_constant_evaluated`] (from C++20)
 * https://en.cppreference.com/w/cpp/types/is_function[`is_function_v`] (implemented with Walter Brown's method)
-* https://en.cppreference.com/w/cpp/types/is_scoped_enum[`is_scoped_enum_v`] (from C++23)
 * https://en.cppreference.com/w/cpp/utility/to_underlying[`to_underlying`] (from C++23)
 * https://en.cppreference.com/w/cpp/types/type_identity[`type_identity`] (from C++20)
 
diff --git a/include/stdx/tuple.hpp b/include/stdx/tuple.hpp
index 59ec39f..adfacb9 100644
--- a/include/stdx/tuple.hpp
+++ b/include/stdx/tuple.hpp
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <stdx/concepts.hpp>
+#include <stdx/ct_conversions.hpp>
 #include <stdx/type_traits.hpp>
 #include <stdx/udls.hpp>
 #include <stdx/utility.hpp>
@@ -27,7 +28,6 @@ template <typename> struct tag_constant;
 template <typename T> constexpr static tag_constant<T> *tag{};
 
 namespace error {
-template <typename...> constexpr auto always_false_v = false;
 template <typename T> struct type_from_tag_constant {
     using type = T;
 };
diff --git a/include/stdx/type_traits.hpp b/include/stdx/type_traits.hpp
index 0ab46de..9381289 100644
--- a/include/stdx/type_traits.hpp
+++ b/include/stdx/type_traits.hpp
@@ -66,10 +66,6 @@ constexpr bool is_function_object_v = detail::is_func_obj<T>;
 template <typename T>
 constexpr bool is_callable_v = is_function_v<T> or is_function_object_v<T>;
 
-constexpr auto is_constant_evaluated() noexcept -> bool {
-    return __builtin_is_constant_evaluated();
-}
-
 template <typename T> struct type_identity {
     using type = T;
 };
@@ -115,12 +111,6 @@ constexpr auto is_specialization_of()
     return {};
 }
 
-template <typename E>
-constexpr bool is_scoped_enum_v =
-    std::is_enum_v<E> and not std::is_convertible_v<E, underlying_type_t<E>>;
-template <typename E>
-using is_scoped_enum = std::bool_constant<is_scoped_enum_v<E>>;
-
 template <typename...> struct type_list {};
 template <auto...> struct value_list {};
 
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index ea04c68..7b497b5 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -53,7 +53,6 @@ add_tests(
     intrusive_forward_list
     intrusive_list
     intrusive_list_properties
-    is_constant_evaluated
     iterator
     latched
     numeric
diff --git a/test/is_constant_evaluated.cpp b/test/is_constant_evaluated.cpp
deleted file mode 100644
index c0e9615..0000000
--- a/test/is_constant_evaluated.cpp
+++ /dev/null
@@ -1,23 +0,0 @@
-#include <stdx/type_traits.hpp>
-
-#include <catch2/catch_test_macros.hpp>
-
-namespace {
-constexpr auto f() -> int {
-    if (stdx::is_constant_evaluated()) {
-        return 42;
-    } else {
-        return 0;
-    }
-}
-} // namespace
-
-TEST_CASE("constexpr context", "[is_constant_evaluated]") {
-    constexpr auto n = f();
-    CHECK(n == 42);
-}
-
-TEST_CASE("runtime context", "[is_constant_evaluated]") {
-    auto n = f();
-    CHECK(n == 0);
-}
diff --git a/test/type_traits.cpp b/test/type_traits.cpp
index 80583ff..ecffbce 100644
--- a/test/type_traits.cpp
+++ b/test/type_traits.cpp
@@ -71,21 +71,6 @@ TEST_CASE("derived types are not specializations (value templates)",
         not stdx::is_specialization_of<value_derived_t<0>, value_unary_t>());
 }
 
-namespace {
-enum E1 {};
-enum struct E2 {};
-} // namespace
-
-TEST_CASE("is_scoped_enum", "[type_traits]") {
-    STATIC_REQUIRE(not stdx::is_scoped_enum_v<int>);
-    STATIC_REQUIRE(not stdx::is_scoped_enum_v<E1>);
-    STATIC_REQUIRE(stdx::is_scoped_enum_v<E2>);
-
-    STATIC_REQUIRE(not stdx::is_scoped_enum<int>::value);
-    STATIC_REQUIRE(not stdx::is_scoped_enum<E1>::value);
-    STATIC_REQUIRE(stdx::is_scoped_enum<E2>::value);
-}
-
 TEST_CASE("type_identity", "[type_traits]") {
     STATIC_REQUIRE(std::is_same_v<stdx::type_identity_t<void>, void>);
 }