diff --git a/include/fmt/chrono.h b/include/fmt/chrono.h
index 46a93fde..ef6a2990 100644
--- a/include/fmt/chrono.h
+++ b/include/fmt/chrono.h
@@ -2071,9 +2071,9 @@ struct formatter<std::chrono::time_point<std::chrono::system_clock, Duration>,
       const auto subsecs = std::chrono::duration_cast<Duration>(
           epoch - std::chrono::duration_cast<std::chrono::seconds>(epoch));
 
-      return formatter<std::tm, Char>::format(
+      return formatter<std::tm, Char>::do_format(
           localtime(std::chrono::time_point_cast<std::chrono::seconds>(val)),
-          ctx, subsecs);
+          ctx, &subsecs);
     }
 
     return formatter<std::tm, Char>::format(
@@ -2117,6 +2117,22 @@ template <typename Char> struct formatter<std::tm, Char> {
     return end;
   }
 
+  template <typename FormatContext, typename Duration>
+  auto do_format(const std::tm& tm, FormatContext& ctx,
+                 const Duration* subsecs) const -> decltype(ctx.out()) {
+    const auto loc_ref = ctx.locale();
+    detail::get_locale loc(static_cast<bool>(loc_ref), loc_ref);
+    auto w = detail::tm_writer<decltype(ctx.out()), Char, Duration>(
+        loc, ctx.out(), tm, subsecs);
+    if (spec_ == spec::year_month_day)
+      w.on_iso_date();
+    else if (spec_ == spec::hh_mm_ss)
+      w.on_iso_time();
+    else
+      detail::parse_chrono_format(specs.begin(), specs.end(), w);
+    return w.out();
+  }
+
  public:
   FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
       -> decltype(ctx.begin()) {
@@ -2134,32 +2150,7 @@ template <typename Char> struct formatter<std::tm, Char> {
   template <typename FormatContext>
   auto format(const std::tm& tm, FormatContext& ctx) const
       -> decltype(ctx.out()) {
-    const auto loc_ref = ctx.locale();
-    detail::get_locale loc(static_cast<bool>(loc_ref), loc_ref);
-    auto w = detail::tm_writer<decltype(ctx.out()), Char>(loc, ctx.out(), tm);
-    if (spec_ == spec::year_month_day)
-      w.on_iso_date();
-    else if (spec_ == spec::hh_mm_ss)
-      w.on_iso_time();
-    else
-      detail::parse_chrono_format(specs.begin(), specs.end(), w);
-    return w.out();
-  }
-
-  template <typename FormatContext, typename Duration>
-  auto format(const std::tm& tm, FormatContext& ctx,
-              const Duration& subsecs) const -> decltype(ctx.out()) {
-    const auto loc_ref = ctx.locale();
-    detail::get_locale loc(static_cast<bool>(loc_ref), loc_ref);
-    auto w = detail::tm_writer<decltype(ctx.out()), Char, Duration>(
-        loc, ctx.out(), tm, &subsecs);
-    if (spec_ == spec::year_month_day)
-      w.on_iso_date();
-    else if (spec_ == spec::hh_mm_ss)
-      w.on_iso_time();
-    else
-      detail::parse_chrono_format(specs.begin(), specs.end(), w);
-    return w.out();
+    return do_format<FormatContext, std::chrono::seconds>(tm, ctx, nullptr);
   }
 };