diff --git a/include/fast_float/ascii_number.h b/include/fast_float/ascii_number.h
index e840d08..f2484e8 100644
--- a/include/fast_float/ascii_number.h
+++ b/include/fast_float/ascii_number.h
@@ -283,7 +283,7 @@ template <typename UC>
 fastfloat_really_inline FASTFLOAT_CONSTEXPR20 parsed_number_string_t<UC>
 parse_number_string(UC const *p, UC const *pend,
                     parse_options_t<UC> options) noexcept {
-  chars_format const fmt = options.format;
+  chars_format const fmt = detail::adjust_for_feature_macros(options.format);
   UC const decimal_point = options.decimal_point;
 
   parsed_number_string_t<UC> answer;
@@ -291,15 +291,10 @@ parse_number_string(UC const *p, UC const *pend,
   answer.too_many_digits = false;
   // assume p < pend, so dereference without checks;
   answer.negative = (*p == UC('-'));
-#ifdef FASTFLOAT_ALLOWS_LEADING_PLUS // disabled by default
-  if ((*p == UC('-')) ||
-      (!uint64_t(fmt & detail::basic_json_fmt) && *p == UC('+'))) {
-#else
   // C++17 20.19.3.(7.1) explicitly forbids '+' sign here
   if ((*p == UC('-')) ||
       (uint64_t(fmt & chars_format::allow_leading_plus) &&
        !uint64_t(fmt & detail::basic_json_fmt) && *p == UC('+'))) {
-#endif
     ++p;
     if (p == pend) {
       return report_parse_error<UC>(
@@ -479,7 +474,7 @@ template <typename T, typename UC>
 fastfloat_really_inline FASTFLOAT_CONSTEXPR20 from_chars_result_t<UC>
 parse_int_string(UC const *p, UC const *pend, T &value,
                  parse_options_t<UC> options) {
-  chars_format const fmt = options.format;
+  chars_format const fmt = detail::adjust_for_feature_macros(options.format);
   int const base = options.base;
 
   from_chars_result_t<UC> answer;
@@ -492,12 +487,8 @@ parse_int_string(UC const *p, UC const *pend, T &value,
     answer.ptr = first;
     return answer;
   }
-#ifdef FASTFLOAT_ALLOWS_LEADING_PLUS // disabled by default
-  if ((*p == UC('-')) || (*p == UC('+'))) {
-#else
   if ((*p == UC('-')) ||
       (uint64_t(fmt & chars_format::allow_leading_plus) && (*p == UC('+')))) {
-#endif
     ++p;
   }
 
diff --git a/include/fast_float/float_common.h b/include/fast_float/float_common.h
index df77a3e..1085fde 100644
--- a/include/fast_float/float_common.h
+++ b/include/fast_float/float_common.h
@@ -841,6 +841,20 @@ operator^=(chars_format &lhs, chars_format rhs) noexcept {
   return lhs = (lhs ^ rhs);
 }
 
+namespace detail {
+// adjust for deprecated feature macros
+constexpr chars_format adjust_for_feature_macros(chars_format fmt) {
+  return fmt
+#ifdef FASTFLOAT_ALLOWS_LEADING_PLUS
+         | chars_format::allow_leading_plus
+#endif
+#ifdef FASTFLOAT_SKIP_WHITE_SPACE
+         | chars_format::skip_white_space
+#endif
+      ;
+}
+} // namespace detail
+
 } // namespace fast_float
 
 #endif
diff --git a/include/fast_float/parse_number.h b/include/fast_float/parse_number.h
index 872d23d..a44c77f 100644
--- a/include/fast_float/parse_number.h
+++ b/include/fast_float/parse_number.h
@@ -27,14 +27,10 @@ from_chars_result_t<UC>
   answer.ec = std::errc(); // be optimistic
   // assume first < last, so dereference without checks;
   bool const minusSign = (*first == UC('-'));
-#ifdef FASTFLOAT_ALLOWS_LEADING_PLUS // disabled by default
-  if ((*first == UC('-')) || (*first == UC('+'))) {
-#else
   // C++17 20.19.3.(7.1) explicitly forbids '+' sign here
   if ((*first == UC('-')) ||
       (uint64_t(fmt & chars_format::allow_leading_plus) &&
        (*first == UC('+')))) {
-#endif
     ++first;
   }
   if (last - first >= 3) {
@@ -294,18 +290,14 @@ from_chars_float_advanced(UC const *first, UC const *last, T &value,
   static_assert(is_supported_char_type<UC>(),
                 "only char, wchar_t, char16_t and char32_t are supported");
 
-  chars_format const fmt = options.format;
+  chars_format const fmt = detail::adjust_for_feature_macros(options.format);
 
   from_chars_result_t<UC> answer;
-#ifndef FASTFLOAT_SKIP_WHITE_SPACE // disabled by default
   if (uint64_t(fmt & chars_format::skip_white_space)) {
-#endif
     while ((first != last) && fast_float::is_space(uint8_t(*first))) {
       first++;
     }
-#ifndef FASTFLOAT_SKIP_WHITE_SPACE // disabled by default
   }
-#endif
   if (first == last) {
     answer.ec = std::errc::invalid_argument;
     answer.ptr = first;
@@ -349,19 +341,15 @@ from_chars_int_advanced(UC const *first, UC const *last, T &value,
   static_assert(is_supported_char_type<UC>(),
                 "only char, wchar_t, char16_t and char32_t are supported");
 
-  chars_format const fmt = options.format;
+  chars_format const fmt = detail::adjust_for_feature_macros(options.format);
   int const base = options.base;
 
   from_chars_result_t<UC> answer;
-#ifndef FASTFLOAT_SKIP_WHITE_SPACE // disabled by default
   if (uint64_t(fmt & chars_format::skip_white_space)) {
-#endif
     while ((first != last) && fast_float::is_space(uint8_t(*first))) {
       first++;
     }
-#ifndef FASTFLOAT_SKIP_WHITE_SPACE // disabled by default
   }
-#endif
   if (first == last || base < 2 || base > 36) {
     answer.ec = std::errc::invalid_argument;
     answer.ptr = first;