diff --git a/include/fmt/time.h b/include/fmt/time.h
index 1a72ebf6..5013914f 100644
--- a/include/fmt/time.h
+++ b/include/fmt/time.h
@@ -31,6 +31,7 @@ inline null<> gmtime_s(...) { return null<>(); }
 
 enum class numeric_system {
   standard,
+  // Alternative numeric system, e.g. 十二 instead of 12 in ja_JP locale.
   alternative
 };
 
@@ -64,10 +65,10 @@ FMT_CONSTEXPR const Char *parse_chrono_format(
       handler.on_full_weekday();
       break;
     case 'w':
-      handler.on_dec0_weekday();
+      handler.on_dec0_weekday(numeric_system::standard);
       break;
     case 'u':
-      handler.on_dec1_weekday();
+      handler.on_dec1_weekday(numeric_system::standard);
       break;
     // Month:
     case 'b':
@@ -95,6 +96,12 @@ FMT_CONSTEXPR const Char *parse_chrono_format(
         throw format_error("invalid format");
       c = *ptr++;
       switch (c) {
+      case 'w':
+        handler.on_dec0_weekday(numeric_system::alternative);
+        break;
+      case 'u':
+        handler.on_dec1_weekday(numeric_system::alternative);
+        break;
       case 'H':
         handler.on_24_hour(numeric_system::alternative);
         break;
@@ -123,8 +130,8 @@ struct chrono_format_checker {
   void on_text(const Char *, const Char *) {}
   void on_abbr_weekday() {}
   void on_full_weekday() {}
-  void on_dec0_weekday() {}
-  void on_dec1_weekday() {}
+  void on_dec0_weekday(numeric_system) {}
+  void on_dec1_weekday(numeric_system) {}
   void on_abbr_month() {}
   void on_full_month() {}
   void on_24_hour(numeric_system) {}
@@ -158,8 +165,8 @@ struct chrono_formatter {
 
   void write(int value, int width) {
     typedef typename int_traits<int>::main_type main_type;
-    main_type n = value;
-    int num_digits = internal::count_digits(n);
+    main_type n = to_unsigned(value);
+    int num_digits = static_cast<int>(internal::count_digits(n));
     if (width > num_digits)
       out = std::fill_n(out, width - num_digits, '0');
     out = format_decimal<char_type>(out, n, num_digits);
@@ -182,8 +189,8 @@ struct chrono_formatter {
 
   void on_abbr_weekday() {}
   void on_full_weekday() {}
-  void on_dec0_weekday() {}
-  void on_dec1_weekday() {}
+  void on_dec0_weekday(numeric_system) {}
+  void on_dec1_weekday(numeric_system) {}
   void on_abbr_month() {}
   void on_full_month() {}
 
@@ -211,16 +218,23 @@ struct chrono_formatter {
     if (ns == numeric_system::standard)
       return write(minute, 2);
     auto time = tm();
-    time.tm_minute = minute;
+    time.tm_min = minute;
     format_localized(time, 'M');
   }
 
-  void on_second(numeric_system) {
-    write(to_int(s.count() % 60), 2);
-    if (ms != std::chrono::milliseconds()) {
-      *out++ = '.';
-      write(to_int(ms.count()), 3);
+  void on_second(numeric_system ns) {
+    auto second = to_int(s.count() % 60);
+    if (ns == numeric_system::standard) {
+      write(second, 2);
+      if (ms != std::chrono::milliseconds()) {
+        *out++ = '.';
+        write(to_int(ms.count()), 3);
+      }
+      return;
     }
+    auto time = tm();
+    time.tm_sec = second;
+    format_localized(time, 'S');
   }
 };
 }  // namespace internal
diff --git a/test/time-test.cc b/test/time-test.cc
index 940ae252..b6fcc401 100644
--- a/test/time-test.cc
+++ b/test/time-test.cc
@@ -82,6 +82,22 @@ TEST(TimeTest, Chrono) {
             fmt::format("{:%H:%M:%S}", std::chrono::seconds(12345)));
 }
 
+std::string format_tm(const std::tm &time, const char *spec,
+                      const std::locale &loc) {
+  std::ostringstream os;
+  os.imbue(loc);
+  os << std::put_time(&time, spec);
+  return os.str();
+}
+
+#define EXPECT_TIME(spec, field, value, duration) { \
+    auto time = std::tm(); \
+    time.field = value; \
+    std::locale("ja_JP.utf8"); \
+    EXPECT_EQ(format_tm(time, spec, loc), \
+              fmt::format(loc, "{:" spec "}", std::chrono::duration(value))); \
+  }
+
 TEST(TimeTest, ChronoLocale) {
   const char *loc_name = "ja_JP.utf8";
   bool has_locale = false;
@@ -94,21 +110,9 @@ TEST(TimeTest, ChronoLocale) {
     fmt::print("{} locale is missing.\n", loc_name);
     return;
   }
-  std::ostringstream os;
-  auto str = [&] {
-    auto s = os.str();
-    os.str("");
-    return s;
-  };
-  os.imbue(loc);
-  auto time = std::tm();
-  time.tm_hour = 14;
-  os << std::put_time(&time, "%OH");
-  EXPECT_EQ(str(), fmt::format(loc, "{:%OH}", std::chrono::hours(14)));
-  os << std::put_time(&time, "%OI");
-  EXPECT_EQ(str(), fmt::format(loc, "{:%OI}", std::chrono::hours(14)));
-  time.tm_minute = 42;
-  os << std::put_time(&time, "%OM");
-  EXPECT_EQ(str(), fmt::format(loc, "{:%OM}", std::chrono::minutes(42)));
+  EXPECT_TIME("%OH", tm_hour, 14, hours);
+  EXPECT_TIME("%OI", tm_hour, 14, hours);
+  EXPECT_TIME("%OM", tm_min, 42, minutes);
+  EXPECT_TIME("%OS", tm_min, 42, seconds);
 }
 #endif