diff --git a/include/fmt/chrono.h b/include/fmt/chrono.h
index a1c13483..66a2fb72 100644
--- a/include/fmt/chrono.h
+++ b/include/fmt/chrono.h
@@ -1681,7 +1681,7 @@ struct duration_formatter {
 
   auto hour12() const -> Rep {
     Rep hour = static_cast<Rep>(mod((s.count() / 3600), 12));
-    return hour <= 0 ? 12 : hour;
+    return hour < 1 ? 12 : hour;
   }
 
   auto minute() const -> Rep {
diff --git a/test/chrono-test.cc b/test/chrono-test.cc
index d9ea18a1..2c54febb 100644
--- a/test/chrono-test.cc
+++ b/test/chrono-test.cc
@@ -507,6 +507,15 @@ TEST(chrono_test, format_specs) {
   EXPECT_EQ(fmt::format("{:%q}", std::chrono::seconds(12345)), "s");
 }
 
+TEST(chrono_test, format_12_hour_fp) {
+  using seconds = std::chrono::duration<double>;
+  EXPECT_EQ(fmt::format("{:%I:%M:%S %p}", seconds(1)), "12:00:01 AM");
+  EXPECT_EQ(fmt::format("{:%I:%M:%S %p}", seconds(43201)), "12:00:01 PM");
+  EXPECT_EQ(fmt::format("{:%I}", seconds(3599)), "12");
+  EXPECT_EQ(fmt::format("{:%I}", seconds(3600)), "01");
+  EXPECT_EQ(fmt::format("{:%I}", seconds(86401)), "12");
+}
+
 TEST(chrono_test, invalid_specs) {
   auto sec = std::chrono::seconds(0);
   EXPECT_THROW_MSG((void)fmt::format(runtime("{:%a}"), sec), fmt::format_error,