diff --git a/include/fast_float/ascii_number.h b/include/fast_float/ascii_number.h
index eba8b9a..417b88b 100644
--- a/include/fast_float/ascii_number.h
+++ b/include/fast_float/ascii_number.h
@@ -273,7 +273,6 @@ 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;
-  parse_rules const rules = options.rules;
   UC const decimal_point = options.decimal_point;
 
   parsed_number_string_t<UC> answer;
@@ -289,12 +288,11 @@ parsed_number_string_t<UC> parse_number_string(UC const *p, UC const * pend, par
     if (p == pend) {
       return answer;
     }
-    if (rules == parse_rules::json) {
+    if (fmt == chars_format::json) {
       if (!is_integer(*p)) { // a sign must be followed by an integer
         return answer;
       }    
     } else {
-      FASTFLOAT_DEBUG_ASSERT(rules == parse_rules::std);
       if (!is_integer(*p) && (*p != decimal_point)) { // a sign must be followed by an integer or the dot
         return answer;
       }
@@ -315,7 +313,7 @@ parsed_number_string_t<UC> parse_number_string(UC const *p, UC const * pend, par
   int64_t digit_count = int64_t(end_of_integer_part - start_digits);
   answer.integer = span<const UC>(start_digits, size_t(digit_count));
   // disallow leading zeros
-  if (rules == parse_rules::json && start_digits[0] == UC('0') && digit_count > 1) {
+  if (fmt == chars_format::json && start_digits[0] == UC('0') && digit_count > 1) {
     return answer;
   }
 
@@ -342,7 +340,7 @@ parsed_number_string_t<UC> parse_number_string(UC const *p, UC const * pend, par
     return answer;
   }
   // or at least two if a decimal point exists, with json rules
-  else if (rules == parse_rules::json && has_decimal_point && digit_count == 1) {
+  else if (fmt == chars_format::json && has_decimal_point && digit_count == 1) {
     return answer;
   }
   int64_t exp_number = 0;            // explicit exponential part
diff --git a/include/fast_float/float_common.h b/include/fast_float/float_common.h
index 466d094..7050073 100644
--- a/include/fast_float/float_common.h
+++ b/include/fast_float/float_common.h
@@ -16,14 +16,10 @@ enum chars_format {
   scientific = 1 << 0,
   fixed = 1 << 2,
   hex = 1 << 3,
+  json = 1 << 4 | fixed | scientific,
   general = fixed | scientific
 };
 
-enum class parse_rules {
-  std,
-  json
-};
-
 template <typename UC>
 struct from_chars_result_t {
   UC const* ptr;
@@ -34,15 +30,13 @@ using from_chars_result = from_chars_result_t<char>;
 template <typename UC>
 struct parse_options_t {
   constexpr explicit parse_options_t(chars_format fmt = chars_format::general,
-    UC dot = UC('.'), parse_rules prules = parse_rules::std)
-    : format(fmt), decimal_point(dot), rules(prules) {}
+    UC dot = UC('.'))
+    : format(fmt), decimal_point(dot) {}
 
   /** Which number formats are accepted */
   chars_format format;
   /** The character used as decimal point */
   UC decimal_point;
-  /** Rules to use for parsing */
-  parse_rules rules;
 };
 using parse_options = parse_options_t<char>;