diff --git a/include/fmt/chrono.h b/include/fmt/chrono.h
index 6610e62e..65f5b5a5 100644
--- a/include/fmt/chrono.h
+++ b/include/fmt/chrono.h
@@ -389,8 +389,8 @@ struct formatter<std::chrono::duration<Rep, Period>, Char> {
       if (const char *unit = get_units<Period>())
         return format_to(ctx.out(), "{}{}", d.count(), unit);
       if (Period::den == 1)
-        return format_to(ctx.out(), "{}[{}s]", d.count(), Period::num);
-      return format_to(ctx.out(), "{}[{}/{}s]",
+        return format_to(ctx.out(), "{}[{}]s", d.count(), Period::num);
+      return format_to(ctx.out(), "{}[{}/{}]s",
                        d.count(), Period::num, Period::den);
     }
     internal::chrono_formatter<FormatContext> f(ctx);
diff --git a/test/chrono-test.cc b/test/chrono-test.cc
index ca25d18c..4e6e97e1 100644
--- a/test/chrono-test.cc
+++ b/test/chrono-test.cc
@@ -83,10 +83,10 @@ TEST(ChronoTest, FormatDefault) {
             fmt::format("{}", std::chrono::duration<int, std::exa>(42)));
   EXPECT_EQ("42m", fmt::format("{}", std::chrono::minutes(42)));
   EXPECT_EQ("42h", fmt::format("{}", std::chrono::hours(42)));
-  EXPECT_EQ("42[15s]",
+  EXPECT_EQ("42[15]s",
             fmt::format("{}",
                         std::chrono::duration<int, std::ratio<15, 1>>(42)));
-  EXPECT_EQ("42[15/4s]",
+  EXPECT_EQ("42[15/4]s",
             fmt::format("{}",
                         std::chrono::duration<int, std::ratio<15, 4>>(42)));
 }