diff --git a/include/fmt/core.h b/include/fmt/core.h
index 2ecb4db6..e17e0702 100644
--- a/include/fmt/core.h
+++ b/include/fmt/core.h
@@ -1927,6 +1927,10 @@ FMT_CONSTEXPR const Char* parse_align(const Char* begin, const Char* end,
 
 struct auto_id {};
 
+template <typename Char> FMT_CONSTEXPR bool is_name_start(Char c) {
+  return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || '_' == c;
+}
+
 template <typename Char, typename IDHandler>
 FMT_CONSTEXPR const Char* do_parse_arg_id(const Char* begin, const Char* end,
                                           IDHandler&& handler) {
diff --git a/include/fmt/format.h b/include/fmt/format.h
index 45e8df26..76fe1444 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -2263,10 +2263,6 @@ class arg_formatter : public arg_formatter_base<OutputIt, Char> {
   }
 };
 
-template <typename Char> FMT_CONSTEXPR bool is_name_start(Char c) {
-  return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || '_' == c;
-}
-
 template <typename Context> class custom_formatter {
  private:
   using char_type = typename Context::char_type;