diff --git a/include/fast_float/ascii_number.h b/include/fast_float/ascii_number.h
index 84bce47..0338b22 100644
--- a/include/fast_float/ascii_number.h
+++ b/include/fast_float/ascii_number.h
@@ -10,7 +10,7 @@
 
 namespace fast_float {
 
-fastfloat_really_inline bool is_integer(char c)  noexcept  { return (c >= '0' && c <= '9'); }
+fastfloat_really_inline bool is_integer(char c)  noexcept  { return (c & 0x30) == 0x30; }
 
 
 // credit: https://johnnylee-sde.github.io/Fast-numeric-string-to-int/
@@ -163,7 +163,7 @@ parsed_number_string parse_number_string(const char *p, const char *pend, chars_
 // This function could be optimized. In particular, we could stop after 19 digits
 // and try to bail out. Furthermore, we should be able to recover the computed
 // exponent from the pass in parse_number_string.
-decimal parse_decimal(const char *p, const char *pend) noexcept {
+fastfloat_really_inline decimal parse_decimal(const char *p, const char *pend) noexcept {
   decimal answer;
   answer.num_digits = 0;
   answer.decimal_point = 0;
diff --git a/include/fast_float/float_common.h b/include/fast_float/float_common.h
index f09d29b..27a3c72 100644
--- a/include/fast_float/float_common.h
+++ b/include/fast_float/float_common.h
@@ -30,7 +30,7 @@ inline bool fastfloat_strncasecmp(const char *input1, const char *input2,
 #error "FLT_EVAL_METHOD should be defined, please include cfloat."
 #endif
 
-bool is_space(uint8_t c) {
+inline bool is_space(uint8_t c) {
   static const bool table[] = {
       0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
@@ -281,7 +281,7 @@ constexpr float binary_format<float>::exact_power_of_ten(int64_t power) {
 
 // for convenience:
 #include <ostream>
-std::ostream &operator<<(std::ostream &out, const fast_float::decimal &d) {
+inline std::ostream &operator<<(std::ostream &out, const fast_float::decimal &d) {
   out << "0.";
   for (size_t i = 0; i < d.num_digits; i++) {
     out << int32_t(d.digits[i]);
diff --git a/include/fast_float/simple_decimal_conversion.h b/include/fast_float/simple_decimal_conversion.h
index 97fad93..f87dbb3 100644
--- a/include/fast_float/simple_decimal_conversion.h
+++ b/include/fast_float/simple_decimal_conversion.h
@@ -123,8 +123,6 @@ uint32_t number_of_digits_decimal_left_shift(const decimal &h, uint32_t shift) {
   return num_new_digits;
 }
 
-} // end of anonymous namespace
-
 uint64_t round(decimal &h) {
   if ((h.num_digits == 0) || (h.decimal_point < 0)) {
     return 0;
@@ -240,6 +238,7 @@ void decimal_right_shift(decimal &h, uint32_t shift) {
   trim(h);
 }
 
+} // end of anonymous namespace
 
 template <typename binary>
 adjusted_mantissa compute_float(decimal &d) {