diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index 3c428e6..03e02b4 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -5,3 +5,4 @@ Neal Richardson
 Tim Paine
 Fabio Pellacini
 Lénárd Szolnoki
+Jan Pharago
\ No newline at end of file
diff --git a/README.md b/README.md
index 1327f5a..fe1c1ca 100644
--- a/README.md
+++ b/README.md
@@ -97,6 +97,24 @@ constexpr double constexptest() {
 }
 ```
 
+## Non-ASCII Inputs
+
+We also support UTF-16 and UTF-32 inputs, as well as ASCII/UTF-8, as in the following example:
+
+``` C++
+#include "fast_float/fast_float.h"
+#include <iostream>
+
+int main() {
+    const std::u16string input =  u"3.1416 xyz ";
+    double result;
+    auto answer = fast_float::from_chars(input.data(), input.data()+input.size(), result);
+    if(answer.ec != std::errc()) { std::cerr << "parsing failure\n"; return EXIT_FAILURE; }
+    std::cout << "parsed the number " << result << std::endl;
+    return EXIT_SUCCESS;
+}
+```
+
 ## Using commas as decimal separator
 
 
diff --git a/include/fast_float/ascii_number.h b/include/fast_float/ascii_number.h
index b7fcc9b..d506326 100644
--- a/include/fast_float/ascii_number.h
+++ b/include/fast_float/ascii_number.h
@@ -12,8 +12,9 @@ namespace fast_float {
 
 // Next function can be micro-optimized, but compilers are entirely
 // able to optimize it well.
-fastfloat_really_inline constexpr bool is_integer(char c) noexcept {
-  return c >= '0' && c <= '9';
+template <typename UC>
+fastfloat_really_inline constexpr bool is_integer(UC c) noexcept {
+  return !(c > UC('9') || c < UC('0'));
 }
 
 fastfloat_really_inline constexpr uint64_t byteswap(uint64_t val) {
@@ -75,6 +76,16 @@ uint32_t parse_eight_digits_unrolled(uint64_t val) {
   return uint32_t(val);
 }
 
+fastfloat_really_inline constexpr
+uint32_t parse_eight_digits_unrolled(const char16_t *)  noexcept  {
+  return 0;
+}
+
+fastfloat_really_inline constexpr
+uint32_t parse_eight_digits_unrolled(const char32_t *)  noexcept  {
+  return 0;
+}
+
 fastfloat_really_inline FASTFLOAT_CONSTEXPR20
 uint32_t parse_eight_digits_unrolled(const char *chars)  noexcept  {
   return parse_eight_digits_unrolled(read_u64(chars));
@@ -86,40 +97,51 @@ fastfloat_really_inline constexpr bool is_made_of_eight_digits_fast(uint64_t val
      0x8080808080808080));
 }
 
+fastfloat_really_inline constexpr
+bool is_made_of_eight_digits_fast(const char16_t *)  noexcept  {
+  return false;
+}
+
+fastfloat_really_inline constexpr
+bool is_made_of_eight_digits_fast(const char32_t *)  noexcept  {
+  return false;
+}
+
 fastfloat_really_inline FASTFLOAT_CONSTEXPR20
 bool is_made_of_eight_digits_fast(const char *chars)  noexcept  {
   return is_made_of_eight_digits_fast(read_u64(chars));
 }
 
-typedef span<const char> byte_span;
-
-struct parsed_number_string {
+template <typename UC>
+struct parsed_number_string_t {
   int64_t exponent{0};
   uint64_t mantissa{0};
-  const char *lastmatch{nullptr};
+  UC const * lastmatch{nullptr};
   bool negative{false};
   bool valid{false};
   bool too_many_digits{false};
   // contains the range of the significant digits
-  byte_span integer{};  // non-nullable
-  byte_span fraction{}; // nullable
+  span<const UC> integer{};  // non-nullable
+  span<const UC> fraction{}; // nullable
 };
-
+using byte_span = span<char>;
+using parsed_number_string = parsed_number_string_t<char>;
 // Assuming that you use no more than 19 digits, this will
 // parse an ASCII string.
+template <typename UC>
 fastfloat_really_inline FASTFLOAT_CONSTEXPR20
-parsed_number_string parse_number_string(const char *p, const char *pend, parse_options options) noexcept {
-  const chars_format fmt = options.format;
-  const char decimal_point = options.decimal_point;
+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;
+  UC const decimal_point = options.decimal_point;
 
-  parsed_number_string answer;
+  parsed_number_string_t<UC> answer;
   answer.valid = false;
   answer.too_many_digits = false;
-  answer.negative = (*p == '-');
+  answer.negative = (*p == UC('-'));
 #ifdef FASTFLOAT_ALLOWS_LEADING_PLUS // disabled by default
-  if ((*p == '-') || (*p == '+')) {
+  if ((*p == UC('-')) || (*p == UC('+'))) {
 #else
-  if (*p == '-') { // C++17 20.19.3.(7.1) explicitly forbids '+' sign here
+  if (*p == UC('-')) { // C++17 20.19.3.(7.1) explicitly forbids '+' sign here
 #endif
     ++p;
     if (p == pend) {
@@ -129,7 +151,7 @@ parsed_number_string parse_number_string(const char *p, const char *pend, parse_
       return answer;
     }
   }
-  const char *const start_digits = p;
+  UC const * const start_digits = p;
 
   uint64_t i = 0; // an unsigned int avoids signed overflows (which are bad)
 
@@ -137,29 +159,31 @@ parsed_number_string parse_number_string(const char *p, const char *pend, parse_
     // a multiplication by 10 is cheaper than an arbitrary integer
     // multiplication
     i = 10 * i +
-        uint64_t(*p - '0'); // might overflow, we will handle the overflow later
+        uint64_t(*p - UC('0')); // might overflow, we will handle the overflow later
     ++p;
   }
-  const char *const end_of_integer_part = p;
+  UC const * const end_of_integer_part = p;
   int64_t digit_count = int64_t(end_of_integer_part - start_digits);
-  answer.integer = byte_span(start_digits, size_t(digit_count));
+  answer.integer = span<const UC>(start_digits, size_t(digit_count));
   int64_t exponent = 0;
   if ((p != pend) && (*p == decimal_point)) {
     ++p;
-    const char* before = p;
+    UC const * before = p;
     // can occur at most twice without overflowing, but let it occur more, since
     // for integers with many digits, digit parsing is the primary bottleneck.
-    while ((std::distance(p, pend) >= 8) && is_made_of_eight_digits_fast(p)) {
-      i = i * 100000000 + parse_eight_digits_unrolled(p); // in rare cases, this will overflow, but that's ok
-      p += 8;
+    if (std::is_same<UC,char>::value) {
+      while ((std::distance(p, pend) >= 8) && is_made_of_eight_digits_fast(p)) {
+        i = i * 100000000 + parse_eight_digits_unrolled(p); // in rare cases, this will overflow, but that's ok
+        p += 8;
+      }
     }
     while ((p != pend) && is_integer(*p)) {
-      uint8_t digit = uint8_t(*p - '0');
+      uint8_t digit = uint8_t(*p - UC('0'));
       ++p;
       i = i * 10 + digit; // in rare cases, this will overflow, but that's ok
     }
     exponent = before - p;
-    answer.fraction = byte_span(before, size_t(p - before));
+    answer.fraction = span<const UC>(before, size_t(p - before));
     digit_count -= exponent;
   }
   // we must have encountered at least one integer!
@@ -167,14 +191,14 @@ parsed_number_string parse_number_string(const char *p, const char *pend, parse_
     return answer;
   }
   int64_t exp_number = 0;            // explicit exponential part
-  if ((fmt & chars_format::scientific) && (p != pend) && (('e' == *p) || ('E' == *p))) {
-    const char * location_of_e = p;
+  if ((fmt & chars_format::scientific) && (p != pend) && ((UC('e') == *p) || (UC('E') == *p))) {
+    UC const * location_of_e = p;
     ++p;
     bool neg_exp = false;
-    if ((p != pend) && ('-' == *p)) {
+    if ((p != pend) && (UC('-') == *p)) {
       neg_exp = true;
       ++p;
-    } else if ((p != pend) && ('+' == *p)) { // '+' on exponent is allowed by C++17 20.19.3.(7.1)
+    } else if ((p != pend) && (UC('+') == *p)) { // '+' on exponent is allowed by C++17 20.19.3.(7.1)
       ++p;
     }
     if ((p == pend) || !is_integer(*p)) {
@@ -186,7 +210,7 @@ parsed_number_string parse_number_string(const char *p, const char *pend, parse_
       p = location_of_e;
     } else {
       while ((p != pend) && is_integer(*p)) {
-        uint8_t digit = uint8_t(*p - '0');
+        uint8_t digit = uint8_t(*p - UC('0'));
         if (exp_number < 0x10000000) {
           exp_number = 10 * exp_number + digit;
         }
@@ -212,9 +236,9 @@ parsed_number_string parse_number_string(const char *p, const char *pend, parse_
     // We have to handle the case where we have 0.0000somenumber.
     // We need to be mindful of the case where we only have zeroes...
     // E.g., 0.000000000...000.
-    const char *start = start_digits;
-    while ((start != pend) && (*start == '0' || *start == decimal_point)) {
-      if(*start == '0') { digit_count --; }
+    UC const * start = start_digits;
+    while ((start != pend) && (*start == UC('0') || *start == decimal_point)) {
+      if(*start == UC('0')) { digit_count --; }
       start++;
     }
     if (digit_count > 19) {
@@ -224,19 +248,19 @@ parsed_number_string parse_number_string(const char *p, const char *pend, parse_
       // pre-tokenized spans from above.
       i = 0;
       p = answer.integer.ptr;
-      const char* int_end = p + answer.integer.len();
+      UC const * int_end = p + answer.integer.len();
       const uint64_t minimal_nineteen_digit_integer{1000000000000000000};
       while((i < minimal_nineteen_digit_integer) && (p != int_end)) {
-        i = i * 10 + uint64_t(*p - '0');
+        i = i * 10 + uint64_t(*p - UC('0'));
         ++p;
       }
       if (i >= minimal_nineteen_digit_integer) { // We have a big integers
         exponent = end_of_integer_part - p + exp_number;
       } else { // We have a value with a fractional component.
           p = answer.fraction.ptr;
-          const char* frac_end = p + answer.fraction.len();
+          UC const * frac_end = p + answer.fraction.len();
           while((i < minimal_nineteen_digit_integer) && (p != frac_end)) {
-            i = i * 10 + uint64_t(*p - '0');
+            i = i * 10 + uint64_t(*p - UC('0'));
             ++p;
           }
           exponent = answer.fraction.ptr - p + exp_number;
diff --git a/include/fast_float/digit_comparison.h b/include/fast_float/digit_comparison.h
index 3959ba0..f469f6b 100644
--- a/include/fast_float/digit_comparison.h
+++ b/include/fast_float/digit_comparison.h
@@ -23,8 +23,9 @@ constexpr static uint64_t powers_of_ten_uint64[] = {
 // this algorithm is not even close to optimized, but it has no practical
 // effect on performance: in order to have a faster algorithm, we'd need
 // to slow down performance for faster algorithms, and this is still fast.
+template <typename UC>
 fastfloat_really_inline FASTFLOAT_CONSTEXPR14
-int32_t scientific_exponent(parsed_number_string& num) noexcept {
+int32_t scientific_exponent(parsed_number_string_t<UC> & num) noexcept {
   uint64_t mantissa = num.mantissa;
   int32_t exponent = int32_t(num.exponent);
   while (mantissa >= 10000) {
@@ -153,19 +154,19 @@ void round_down(adjusted_mantissa& am, int32_t shift) noexcept {
   }
   am.power2 += shift;
 }
-
+template <typename UC>
 fastfloat_really_inline FASTFLOAT_CONSTEXPR20
-void skip_zeros(const char*& first, const char* last) noexcept {
+void skip_zeros(UC const * & first, UC const * last) noexcept {
   uint64_t val;
-  while (!cpp20_and_in_constexpr() && std::distance(first, last) >= 8) {
+  while (!cpp20_and_in_constexpr() && std::distance(first, last) >= int_cmp_len<UC>()) {
     ::memcpy(&val, first, sizeof(uint64_t));
-    if (val != 0x3030303030303030) {
+    if (val != int_cmp_zeros<UC>()) {
       break;
     }
-    first += 8;
+    first += int_cmp_len<UC>();
   }
   while (first != last) {
-    if (*first != '0') {
+    if (*first != UC('0')) {
       break;
     }
     first++;
@@ -174,29 +175,40 @@ void skip_zeros(const char*& first, const char* last) noexcept {
 
 // determine if any non-zero digits were truncated.
 // all characters must be valid digits.
+template <typename UC>
 fastfloat_really_inline FASTFLOAT_CONSTEXPR20
-bool is_truncated(const char* first, const char* last) noexcept {
+bool is_truncated(UC const * first, UC const * last) noexcept {
   // do 8-bit optimizations, can just compare to 8 literal 0s.
   uint64_t val;
-  while (!cpp20_and_in_constexpr() && std::distance(first, last) >= 8) {
+  while (!cpp20_and_in_constexpr() && std::distance(first, last) >= int_cmp_len<UC>()) {
     ::memcpy(&val, first, sizeof(uint64_t));
-    if (val != 0x3030303030303030) {
+    if (val != int_cmp_zeros<UC>()) {
       return true;
     }
-    first += 8;
+    first += int_cmp_len<UC>();
   }
   while (first != last) {
-    if (*first != '0') {
+    if (*first != UC('0')) {
       return true;
     }
-    first++;
+    ++first;
   }
   return false;
 }
+template <typename UC>
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20
+bool is_truncated(span<const UC> s) noexcept {
+  return is_truncated(s.ptr, s.ptr + s.len());
+}
 
 fastfloat_really_inline FASTFLOAT_CONSTEXPR20
-bool is_truncated(byte_span s) noexcept {
-  return is_truncated(s.ptr, s.ptr + s.len());
+void parse_eight_digits(const char16_t*& , limb& , size_t& , size_t& ) noexcept {
+  // currently unused
+}
+
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20
+void parse_eight_digits(const char32_t*& , limb& , size_t& , size_t& ) noexcept {
+  // currently unused
 }
 
 fastfloat_really_inline FASTFLOAT_CONSTEXPR20
@@ -207,9 +219,10 @@ void parse_eight_digits(const char*& p, limb& value, size_t& counter, size_t& co
   count += 8;
 }
 
+template <typename UC>
 fastfloat_really_inline FASTFLOAT_CONSTEXPR14
-void parse_one_digit(const char*& p, limb& value, size_t& counter, size_t& count) noexcept {
-  value = value * 10 + limb(*p - '0');
+void parse_one_digit(UC const *& p, limb& value, size_t& counter, size_t& count) noexcept {
+  value = value * 10 + limb(*p - UC('0'));
   p++;
   counter++;
   count++;
@@ -230,8 +243,9 @@ void round_up_bigint(bigint& big, size_t& count) noexcept {
 }
 
 // parse the significant digits into a big integer
+template <typename UC>
 inline FASTFLOAT_CONSTEXPR20
-void parse_mantissa(bigint& result, parsed_number_string& num, size_t max_digits, size_t& digits) noexcept {
+void parse_mantissa(bigint& result, parsed_number_string_t<UC>& num, size_t max_digits, size_t& digits) noexcept {
   // try to minimize the number of big integer and scalar multiplication.
   // therefore, try to parse 8 digits at a time, and multiply by the largest
   // scalar value (9 or 19 digits) for each step.
@@ -245,13 +259,15 @@ void parse_mantissa(bigint& result, parsed_number_string& num, size_t max_digits
 #endif
 
   // process all integer digits.
-  const char* p = num.integer.ptr;
-  const char* pend = p + num.integer.len();
+  UC const * p = num.integer.ptr;
+  UC const * pend = p + num.integer.len();
   skip_zeros(p, pend);
   // process all digits, in increments of step per loop
   while (p != pend) {
-    while ((std::distance(p, pend) >= 8) && (step - counter >= 8) && (max_digits - digits >= 8)) {
-      parse_eight_digits(p, value, counter, digits);
+    if (std::is_same<UC,char>::value) {
+      while ((std::distance(p, pend) >= 8) && (step - counter >= 8) && (max_digits - digits >= 8)) {
+        parse_eight_digits(p, value, counter, digits);
+      }
     }
     while (counter < step && p != pend && digits < max_digits) {
       parse_one_digit(p, value, counter, digits);
@@ -283,8 +299,10 @@ void parse_mantissa(bigint& result, parsed_number_string& num, size_t max_digits
     }
     // process all digits, in increments of step per loop
     while (p != pend) {
-      while ((std::distance(p, pend) >= 8) && (step - counter >= 8) && (max_digits - digits >= 8)) {
-        parse_eight_digits(p, value, counter, digits);
+      if (std::is_same<UC,char>::value) {
+        while ((std::distance(p, pend) >= 8) && (step - counter >= 8) && (max_digits - digits >= 8)) {
+          parse_eight_digits(p, value, counter, digits);
+        }
       }
       while (counter < step && p != pend && digits < max_digits) {
         parse_one_digit(p, value, counter, digits);
@@ -395,9 +413,9 @@ adjusted_mantissa negative_digit_comp(bigint& bigmant, adjusted_mantissa am, int
 // `b` as a big-integer type, scaled to the same binary exponent as
 // the actual digits. we then compare the big integer representations
 // of both, and use that to direct rounding.
-template <typename T>
+template <typename T, typename UC>
 inline FASTFLOAT_CONSTEXPR20
-adjusted_mantissa digit_comp(parsed_number_string& num, adjusted_mantissa am) noexcept {
+adjusted_mantissa digit_comp(parsed_number_string_t<UC>& num, adjusted_mantissa am) noexcept {
   // remove the invalid exponent bias
   am.power2 -= invalid_am_bias;
 
diff --git a/include/fast_float/fast_float.h b/include/fast_float/fast_float.h
index 65704da..1cc25f4 100644
--- a/include/fast_float/fast_float.h
+++ b/include/fast_float/fast_float.h
@@ -13,22 +13,25 @@ enum chars_format {
     general = fixed | scientific
 };
 
-
-struct from_chars_result {
-  const char *ptr;
+template <typename UC>
+struct from_chars_result_t {
+  UC const * ptr;
   std::errc ec;
 };
+using from_chars_result = from_chars_result_t<char>;
 
-struct parse_options {
-  constexpr explicit parse_options(chars_format fmt = chars_format::general,
-                         char dot = '.')
+template <typename UC>
+struct parse_options_t {
+  constexpr explicit parse_options_t(chars_format fmt = chars_format::general,
+                         UC dot = UC('.'))
     : format(fmt), decimal_point(dot) {}
 
   /** Which number formats are accepted */
   chars_format format;
   /** The character used as decimal point */
-  char decimal_point;
+  UC decimal_point;
 };
+using parse_options = parse_options_t<char>;
 
 /**
  * This function parses the character sequence [first,last) for a number. It parses floating-point numbers expecting
@@ -49,18 +52,18 @@ struct parse_options {
  * to determine whether we allow the fixed point and scientific notation respectively.
  * The default is  `fast_float::chars_format::general` which allows both `fixed` and `scientific`.
  */
-template<typename T>
+template<typename T, typename UC = char>
 FASTFLOAT_CONSTEXPR20
-from_chars_result from_chars(const char *first, const char *last,
+from_chars_result_t<UC> from_chars(UC const * first, UC const * last,
                              T &value, chars_format fmt = chars_format::general)  noexcept;
 
 /**
  * Like from_chars, but accepts an `options` argument to govern number parsing.
  */
-template<typename T>
+template<typename T, typename UC = char>
 FASTFLOAT_CONSTEXPR20
-from_chars_result from_chars_advanced(const char *first, const char *last,
-                                      T &value, parse_options options)  noexcept;
+from_chars_result_t<UC> from_chars_advanced(UC const * first, UC const * last,
+                                      T &value, parse_options_t<UC> options)  noexcept;
 
 } // namespace fast_float
 #include "parse_number.h"
diff --git a/include/fast_float/float_common.h b/include/fast_float/float_common.h
index 0f81f1a..6901d7c 100644
--- a/include/fast_float/float_common.h
+++ b/include/fast_float/float_common.h
@@ -106,11 +106,12 @@ fastfloat_really_inline constexpr bool cpp20_and_in_constexpr() {
 }
 
 // Compares two ASCII strings in a case insensitive manner.
+template <typename UC>
 inline FASTFLOAT_CONSTEXPR14 bool
-fastfloat_strncasecmp(const char *input1, const char *input2, size_t length) {
+fastfloat_strncasecmp(UC const * input1, UC const * input2, size_t length) {
   char running_diff{0};
-  for (size_t i = 0; i < length; i++) {
-    running_diff |= (input1[i] ^ input2[i]);
+  for (size_t i = 0; i < length; ++i) {
+    running_diff |= (char(input1[i]) ^ char(input2[i]));
   }
   return (running_diff == 0) || (running_diff == 32);
 }
@@ -503,6 +504,68 @@ constexpr bool space_lut<T>::value[];
 
 inline constexpr bool is_space(uint8_t c) { return space_lut<>::value[c]; }
 #endif
+
+template<typename UC>
+static constexpr uint64_t int_cmp_zeros()
+{
+    static_assert((sizeof(UC) == 1) || (sizeof(UC) == 2) || (sizeof(UC) == 4), "Unsupported character size");
+    return (sizeof(UC) == 1) ? 0x3030303030303030 : (sizeof(UC) == 2) ? (uint64_t(UC('0')) << 48 | uint64_t(UC('0')) << 32 | uint64_t(UC('0')) << 16 | UC('0')) : (uint64_t(UC('0')) << 32 | UC('0'));
+}
+template<typename UC>
+static constexpr int int_cmp_len()
+{
+    return sizeof(uint64_t) / sizeof(UC);
+}
+template<typename UC>
+static constexpr UC const * str_const_nan()
+{
+    return nullptr;
+}
+template<>
+constexpr char const * str_const_nan<char>()
+{
+    return "nan";
+}
+template<>
+constexpr wchar_t const * str_const_nan<wchar_t>()
+{
+    return L"nan";
+}
+template<>
+constexpr char16_t const * str_const_nan<char16_t>()
+{
+    return u"nan";
+}
+template<>
+constexpr char32_t const * str_const_nan<char32_t>()
+{
+    return U"nan";
+}
+template<typename UC>
+static constexpr UC const * str_const_inf()
+{
+    return nullptr;
+}
+template<>
+constexpr char const * str_const_inf<char>()
+{
+    return "infinity";
+}
+template<>
+constexpr wchar_t const * str_const_inf<wchar_t>()
+{
+    return L"infinity";
+}
+template<>
+constexpr char16_t const * str_const_inf<char16_t>()
+{
+    return u"infinity";
+}
+template<>
+constexpr char32_t const * str_const_inf<char32_t>()
+{
+    return U"infinity";
+}
 } // namespace fast_float
 
 #endif
diff --git a/include/fast_float/parse_number.h b/include/fast_float/parse_number.h
index 5c28910..726d761 100644
--- a/include/fast_float/parse_number.h
+++ b/include/fast_float/parse_number.h
@@ -19,41 +19,41 @@ namespace detail {
  * The case comparisons could be made much faster given that we know that the
  * strings a null-free and fixed.
  **/
-template <typename T>
-from_chars_result FASTFLOAT_CONSTEXPR14
-parse_infnan(const char *first, const char *last, T &value)  noexcept  {
-  from_chars_result answer{};
+template <typename T, typename UC>
+from_chars_result_t<UC> FASTFLOAT_CONSTEXPR14
+parse_infnan(UC const * first, UC const * last, T &value)  noexcept  {
+  from_chars_result_t<UC> answer{};
   answer.ptr = first;
   answer.ec = std::errc(); // be optimistic
   bool minusSign = false;
-  if (*first == '-') { // assume first < last, so dereference without checks; C++17 20.19.3.(7.1) explicitly forbids '+' here
+  if (*first == UC('-')) { // assume first < last, so dereference without checks; C++17 20.19.3.(7.1) explicitly forbids '+' here
       minusSign = true;
       ++first;
   }
 #ifdef FASTFLOAT_ALLOWS_LEADING_PLUS // disabled by default
-  if (*first == '+') {
+  if (*first == UC('+')) {
       ++first;
   }
 #endif
   if (last - first >= 3) {
-    if (fastfloat_strncasecmp(first, "nan", 3)) {
+    if (fastfloat_strncasecmp(first, str_const_nan<UC>(), 3)) {
       answer.ptr = (first += 3);
       value = minusSign ? -std::numeric_limits<T>::quiet_NaN() : std::numeric_limits<T>::quiet_NaN();
       // Check for possible nan(n-char-seq-opt), C++17 20.19.3.7, C11 7.20.1.3.3. At least MSVC produces nan(ind) and nan(snan).
-      if(first != last && *first == '(') {
-        for(const char* ptr = first + 1; ptr != last; ++ptr) {
-          if (*ptr == ')') {
+      if(first != last && *first == UC('(')) {
+        for(UC const * ptr = first + 1; ptr != last; ++ptr) {
+          if (*ptr == UC(')')) {
             answer.ptr = ptr + 1; // valid nan(n-char-seq-opt)
             break;
           }
-          else if(!(('a' <= *ptr && *ptr <= 'z') || ('A' <= *ptr && *ptr <= 'Z') || ('0' <= *ptr && *ptr <= '9') || *ptr == '_'))
+          else if(!((UC('a') <= *ptr && *ptr <= UC('z')) || (UC('A') <= *ptr && *ptr <= UC('Z')) || (UC('0') <= *ptr && *ptr <= UC('9')) || *ptr == UC('_')))
             break; // forbidden char, not nan(n-char-seq-opt)
         }
       }
       return answer;
     }
-    if (fastfloat_strncasecmp(first, "inf", 3)) {
-      if ((last - first >= 8) && fastfloat_strncasecmp(first + 3, "inity", 5)) {
+    if (fastfloat_strncasecmp(first, str_const_inf<UC>(), 3)) {
+      if ((last - first >= 8) && fastfloat_strncasecmp(first + 3, str_const_inf<UC>() + 3, 5)) {
         answer.ptr = first + 8;
       } else {
         answer.ptr = first + 3;
@@ -132,22 +132,25 @@ fastfloat_really_inline bool rounds_to_nearest() noexcept {
 
 } // namespace detail
 
-template<typename T>
+template<typename T, typename UC>
 FASTFLOAT_CONSTEXPR20
-from_chars_result from_chars(const char *first, const char *last,
+from_chars_result_t<UC> from_chars(UC const * first, UC const * last,
                              T &value, chars_format fmt /*= chars_format::general*/)  noexcept  {
-  return from_chars_advanced(first, last, value, parse_options{fmt});
+  return from_chars_advanced(first, last, value, parse_options_t<UC>{fmt});
 }
 
-template<typename T>
+template<typename T, typename UC>
 FASTFLOAT_CONSTEXPR20
-from_chars_result from_chars_advanced(const char *first, const char *last,
-                                      T &value, parse_options options)  noexcept  {
+from_chars_result_t<UC> from_chars_advanced(UC const * first, UC const * last,
+                                      T &value, parse_options_t<UC> options)  noexcept  {
 
   static_assert (std::is_same<T, double>::value || std::is_same<T, float>::value, "only float and double are supported");
+  static_assert (std::is_same<UC, char>::value ||
+                 std::is_same<UC, wchar_t>::value ||
+                 std::is_same<UC, char16_t>::value ||
+                 std::is_same<UC, char32_t>::value , "only char, wchar_t, char16_t and char32_t are supported");
 
-
-  from_chars_result answer;
+  from_chars_result_t<UC> answer;
 #ifdef FASTFLOAT_SKIP_WHITE_SPACE  // disabled by default
   while ((first != last) && fast_float::is_space(uint8_t(*first))) {
     first++;
@@ -158,7 +161,7 @@ from_chars_result from_chars_advanced(const char *first, const char *last,
     answer.ptr = first;
     return answer;
   }
-  parsed_number_string pns = parse_number_string(first, last, options);
+  parsed_number_string_t<UC> pns = parse_number_string<UC>(first, last, options);
   if (!pns.valid) {
     return detail::parse_infnan(first, last, value);
   }
diff --git a/tests/basictest.cpp b/tests/basictest.cpp
index 1f8d5d1..3d7f753 100644
--- a/tests/basictest.cpp
+++ b/tests/basictest.cpp
@@ -644,9 +644,9 @@ enum class Diag { runtime, comptime };
 
 } // anonymous namespace
 
-template <Diag diag, class T>
-constexpr void check_basic_test_result(std::string_view str,
-                                       fast_float::from_chars_result result,
+template <Diag diag, class T, typename result_type, typename stringtype>
+constexpr void check_basic_test_result(stringtype str,
+                                       result_type result,
                                        T actual, T expected, std::errc expected_ec) {
   if constexpr (diag == Diag::runtime) {
       INFO(
@@ -702,11 +702,33 @@ constexpr void check_basic_test_result(std::string_view str,
 #undef FASTFLOAT_CHECK_EQ
 }
 
+
 template<Diag diag, class T>
 constexpr void basic_test(std::string_view str, T expected, std::errc expected_ec = std::errc()) {
   T actual;
   auto result = fast_float::from_chars(str.data(), str.data() + str.size(), actual);
   check_basic_test_result<diag>(str, result, actual, expected, expected_ec);
+  constexpr size_t global_string_capacity = 2048;
+
+  if(str.size() > global_string_capacity) {
+    return;
+  }
+  // We give plenty of memory: 2048 characters.
+  char16_t u16[global_string_capacity]{};
+
+  for (size_t i = 0; i < str.size(); i++) {
+    u16[i] = char16_t(str[i]);
+  }
+  auto result16 = fast_float::from_chars(u16, u16 + str.size(), actual);
+  check_basic_test_result<diag>(std::u16string_view(u16, str.size()), result16, actual, expected, expected_ec);
+
+  char32_t u32[global_string_capacity]{};
+
+  for (size_t i = 0; i < str.size(); i++) {
+    u32[i] = char32_t(str[i]);
+  }
+  auto result32 = fast_float::from_chars(u32, u32 + str.size(), actual);
+  check_basic_test_result<diag>(std::u32string_view(u32, str.size()), result32, actual, expected, expected_ec);
 }
 
 template<Diag diag, class T>