diff --git a/include/spdlog/common-inl.h b/include/spdlog/common-inl.h
index 378efe60..3632ec94 100644
--- a/include/spdlog/common-inl.h
+++ b/include/spdlog/common-inl.h
@@ -60,7 +60,7 @@ SPDLOG_INLINE spdlog_ex::spdlog_ex(std::string msg)
 SPDLOG_INLINE spdlog_ex::spdlog_ex(const std::string &msg, int last_errno)
 {
     memory_buf_t outbuf;
-    fmt::format_system_error(outbuf, last_errno, msg);
+    fmt::format_system_error(outbuf, last_errno, msg.c_str());
     msg_ = fmt::to_string(outbuf);
 }
 
diff --git a/src/fmt.cpp b/src/fmt.cpp
index 9e91beb1..edd52dd5 100644
--- a/src/fmt.cpp
+++ b/src/fmt.cpp
@@ -10,94 +10,58 @@
 #include <spdlog/fmt/bundled/format-inl.h>
 
 
+
 FMT_BEGIN_NAMESPACE
 namespace detail {
 
-template <typename T>
-int format_float(char* buf, std::size_t size, const char* format, int precision,
-                 T value) {
-#ifdef FMT_FUZZ
-  if (precision > 100000)
-    throw std::runtime_error(
-        "fuzz mode - avoid large allocation inside snprintf");
-#endif
-  // Suppress the warning about nonliteral format string.
-  int (*snprintf_ptr)(char*, size_t, const char*, ...) = FMT_SNPRINTF;
-  return precision < 0 ? snprintf_ptr(buf, size, format, value)
-                       : snprintf_ptr(buf, size, format, precision, value);
+template<typename T>
+int format_float(char *buf, std::size_t size, const char *format, int precision, T value)
+{
+#    ifdef FMT_FUZZ
+    if (precision > 100000)
+        throw std::runtime_error("fuzz mode - avoid large allocation inside snprintf");
+#    endif
+    // Suppress the warning about nonliteral format string.
+    int (*snprintf_ptr)(char *, size_t, const char *, ...) = FMT_SNPRINTF;
+    return precision < 0 ? snprintf_ptr(buf, size, format, value) : snprintf_ptr(buf, size, format, precision, value);
 }
 
-template FMT_API dragonbox::decimal_fp<float> dragonbox::to_decimal(float x)
-    FMT_NOEXCEPT;
-template FMT_API dragonbox::decimal_fp<double> dragonbox::to_decimal(double x)
-    FMT_NOEXCEPT;
-
-// DEPRECATED! This function exists for ABI compatibility.
-template <typename Char>
-typename basic_format_context<std::back_insert_iterator<buffer<Char>>,
-                              Char>::iterator
-vformat_to(buffer<Char>& buf, basic_string_view<Char> format_str,
-           basic_format_args<basic_format_context<
-               std::back_insert_iterator<buffer<type_identity_t<Char>>>,
-               type_identity_t<Char>>>
-               args) {
-  using iterator = std::back_insert_iterator<buffer<char>>;
-  using context = basic_format_context<
-      std::back_insert_iterator<buffer<type_identity_t<Char>>>,
-      type_identity_t<Char>>;
-  auto out = iterator(buf);
-  format_handler<iterator, Char, context> h(out, format_str, args, {});
-  parse_format_string<false>(format_str, h);
-  return out;
-}
-template basic_format_context<std::back_insert_iterator<buffer<char>>,
-                              char>::iterator
-vformat_to(buffer<char>&, string_view,
-           basic_format_args<basic_format_context<
-               std::back_insert_iterator<buffer<type_identity_t<char>>>,
-               type_identity_t<char>>>);
-}  // namespace detail
-
-template struct FMT_INSTANTIATION_DEF_API detail::basic_data<void>;
+template FMT_API dragonbox::decimal_fp<float> dragonbox::to_decimal(float x) FMT_NOEXCEPT;
+template FMT_API dragonbox::decimal_fp<double> dragonbox::to_decimal(double x) FMT_NOEXCEPT;
+} // namespace detail
 
 // Workaround a bug in MSVC2013 that prevents instantiation of format_float.
-int (*instantiate_format_float)(double, int, detail::float_specs,
-                                detail::buffer<char>&) = detail::format_float;
+int (*instantiate_format_float)(double, int, detail::float_specs, detail::buffer<char> &) = detail::format_float;
 
-#ifndef FMT_STATIC_THOUSANDS_SEPARATOR
-template FMT_API detail::locale_ref::locale_ref(const std::locale& loc);
+#    ifndef FMT_STATIC_THOUSANDS_SEPARATOR
+template FMT_API detail::locale_ref::locale_ref(const std::locale &loc);
 template FMT_API std::locale detail::locale_ref::get<std::locale>() const;
-#endif
+#    endif
 
 // Explicit instantiations for char.
 
-template FMT_API std::string detail::grouping_impl<char>(locale_ref);
-template FMT_API char detail::thousands_sep_impl(locale_ref);
+template FMT_API auto detail::thousands_sep_impl(locale_ref) -> thousands_sep_result<char>;
 template FMT_API char detail::decimal_point_impl(locale_ref);
 
-template FMT_API void detail::buffer<char>::append(const char*, const char*);
+template FMT_API void detail::buffer<char>::append(const char *, const char *);
 
 template FMT_API void detail::vformat_to(
-    detail::buffer<char>&, string_view,
-    basic_format_args<FMT_BUFFER_CONTEXT(char)>, detail::locale_ref);
-
-template FMT_API int detail::snprintf_float(double, int, detail::float_specs,
-                                            detail::buffer<char>&);
-template FMT_API int detail::snprintf_float(long double, int,
-                                            detail::float_specs,
-                                            detail::buffer<char>&);
-template FMT_API int detail::format_float(double, int, detail::float_specs,
-                                          detail::buffer<char>&);
-template FMT_API int detail::format_float(long double, int, detail::float_specs,
-                                          detail::buffer<char>&);
+    detail::buffer<char> &, string_view, basic_format_args<FMT_BUFFER_CONTEXT(char)>, detail::locale_ref);
+
+template FMT_API int detail::snprintf_float(double, int, detail::float_specs, detail::buffer<char> &);
+template FMT_API int detail::snprintf_float(long double, int, detail::float_specs, detail::buffer<char> &);
+template FMT_API int detail::format_float(double, int, detail::float_specs, detail::buffer<char> &);
+template FMT_API int detail::format_float(long double, int, detail::float_specs, detail::buffer<char> &);
 
 // Explicit instantiations for wchar_t.
 
-template FMT_API std::string detail::grouping_impl<wchar_t>(locale_ref);
-template FMT_API wchar_t detail::thousands_sep_impl(locale_ref);
+template FMT_API auto detail::thousands_sep_impl(locale_ref) -> thousands_sep_result<wchar_t>;
 template FMT_API wchar_t detail::decimal_point_impl(locale_ref);
 
-template FMT_API void detail::buffer<wchar_t>::append(const wchar_t*,
-                                                      const wchar_t*);
+template FMT_API void detail::buffer<wchar_t>::append(const wchar_t *, const wchar_t *);
+
+template struct detail::basic_data<void>;
+
 FMT_END_NAMESPACE
+
 #endif // !SPDLOG_FMT_EXTERNAL