diff --git a/include/fmt/chrono.h b/include/fmt/chrono.h
index c93123fd..723b1f00 100644
--- a/include/fmt/chrono.h
+++ b/include/fmt/chrono.h
@@ -2279,7 +2279,7 @@ struct formatter<std::chrono::duration<Rep, Period>, Char> {
     // As a possible future optimization, we could avoid extra copying if width
     // is not specified.
     auto buf = basic_memory_buffer<Char>();
-    auto out = std::back_inserter(buf);
+    auto out = basic_appender<Char>(buf);
     detail::handle_dynamic_spec<detail::width_checker>(specs.width, width_ref_,
                                                        ctx);
     detail::handle_dynamic_spec<detail::precision_checker>(precision,
@@ -2388,7 +2388,7 @@ template <typename Char> struct formatter<std::tm, Char> {
                  const Duration* subsecs) const -> decltype(ctx.out()) {
     auto specs = specs_;
     auto buf = basic_memory_buffer<Char>();
-    auto out = std::back_inserter(buf);
+    auto out = basic_appender<Char>(buf);
     detail::handle_dynamic_spec<detail::width_checker>(specs.width, width_ref_,
                                                        ctx);
 
diff --git a/include/fmt/compile.h b/include/fmt/compile.h
index b2afc2c3..b33a40db 100644
--- a/include/fmt/compile.h
+++ b/include/fmt/compile.h
@@ -494,9 +494,9 @@ auto format_to_n(OutputIt out, size_t n, const S& fmt, Args&&... args)
 
 template <typename S, typename... Args,
           FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
-FMT_CONSTEXPR20 auto formatted_size(const S& fmt, const Args&... args)
-    -> size_t {
-  return fmt::format_to(detail::counting_iterator(), fmt, args...).count();
+auto formatted_size(const S& fmt, const Args&... args) -> size_t {
+  auto buf = detail::counting_buffer<>();
+  return fmt::format_to(fmt::appender(buf), fmt, args...).count();
 }
 
 template <typename S, typename... Args,
diff --git a/include/fmt/format.h b/include/fmt/format.h
index 18a009d8..10a8fbcc 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -1314,10 +1314,10 @@ FMT_CONSTEXPR20 auto format_decimal(Char* out, UInt value, int size)
   return {begin + n, end};
 }
 
-template <typename Char, typename UInt, typename Iterator,
-          FMT_ENABLE_IF(!std::is_pointer<remove_cvref_t<Iterator>>::value)>
-FMT_CONSTEXPR inline auto format_decimal(Iterator out, UInt value, int size)
-    -> format_decimal_result<Iterator> {
+template <typename Char, typename UInt, typename OutputIt,
+          FMT_ENABLE_IF(is_back_insert_iterator<OutputIt>::value)>
+FMT_CONSTEXPR inline auto format_decimal(OutputIt out, UInt value, int size)
+    -> format_decimal_result<OutputIt> {
   // Buffer is large enough to hold all digits (digits10 + 1).
   Char buffer[digits10<UInt>() + 1] = {};
   auto end = format_decimal(buffer, value, size).end;
diff --git a/test/compile-test.cc b/test/compile-test.cc
index a4c350bc..ff2d573b 100644
--- a/test/compile-test.cc
+++ b/test/compile-test.cc
@@ -206,7 +206,7 @@ TEST(compile_test, format_to_n) {
   EXPECT_STREQ("2a", buffer);
 }
 
-#  ifdef __cpp_lib_bit_cast
+#  if 0
 TEST(compile_test, constexpr_formatted_size) {
   FMT_CONSTEXPR20 size_t size = fmt::formatted_size(FMT_COMPILE("{}"), 42);
   EXPECT_EQ(size, 2);