diff --git a/include/fast_float/constexpr_feature_detect.h b/include/fast_float/constexpr_feature_detect.h
index 57b7d52..d4399b0 100644
--- a/include/fast_float/constexpr_feature_detect.h
+++ b/include/fast_float/constexpr_feature_detect.h
@@ -23,8 +23,10 @@
 #if defined(__cpp_lib_is_constant_evaluated) &&                                \
     __cpp_lib_is_constant_evaluated >= 201811L
 #define FASTFLOAT_HAS_IS_CONSTANT_EVALUATED 1
+#define FASTFLOAT_CONSTEVAL consteval
 #else
 #define FASTFLOAT_HAS_IS_CONSTANT_EVALUATED 0
+#define FASTFLOAT_CONSTEVAL FASTFLOAT_CONSTEXPR14
 #endif
 
 #if defined(__cpp_lib_byteswap)
@@ -58,24 +60,10 @@
 
 
 // For support attribute [[assume]] is declared in P1774
-#if 1 // TODO needs platform specific tests for this
-#define FASTFLOAT_ASSUME(expr)
-#elif defined(__cpp_attrubute_assume)
+#if defined(__cpp_attrubute_assume)
 #define FASTFLOAT_ASSUME(expr) [[assume(expr)]]
-#elif defined(__clang__) // needs testing
-#define FASTFLOAT_ASSUME(expr) __builtin_assume(expr)
-#elif defined(__GNUC__) && !defined(__ICC) // needs testing
-#define FASTFLOAT_ASSUME(expr)                                                 \
-  if (expr) {                                                                  \
-  } else {                                                                     \
-    __builtin_unreachable();                                                   \
-  }
-#elif defined(__ICC) // needs testing
-#define FASTFLOAT_ASSUME(expr) __assume(expr)
-#elif defined(_MSC_VER) // needs testing
-/* currently disable, because MSVC is generated slower code when enabled,
-it's probably reason why MSVC doesnt have [[assume]] */
-#define FASTFLOAT_ASSUME(expr) /*__assume(expr)*/
+#else
+#define FASTFLOAT_ASSUME(expr)
 #endif
 
 #endif // FASTFLOAT_CONSTEXPR_FEATURE_DETECT_H