diff --git a/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GenerateUnicodeDateTimeFormat.cpp b/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GenerateUnicodeDateTimeFormat.cpp
index c0dfece74b..ab6f3847b3 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GenerateUnicodeDateTimeFormat.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GenerateUnicodeDateTimeFormat.cpp
@@ -2289,14 +2289,18 @@ Optional<StringView> get_calendar_day_period_symbol_for_hour(StringView locale,
 
     for (auto day_period_index : day_periods) {
         auto day_period = s_day_periods[day_period_index];
-        auto h = hour;
+        bool hour_falls_within_day_period = false;
 
         if (day_period.begin > day_period.end) {
-            day_period.end += 24;
-            h += 24;
+            if (hour >= day_period.begin)
+                hour_falls_within_day_period = true;
+            else if (hour <= day_period.end)
+                hour_falls_within_day_period = true;
+        } else if ((day_period.begin <= hour) && (hour < day_period.end)) {
+            hour_falls_within_day_period = true;
         }
 
-        if ((day_period.begin <= h) && (h < day_period.end)) {
+        if (hour_falls_within_day_period) {
             auto period = static_cast<DayPeriod>(day_period.day_period);
             return get_calendar_day_period_symbol(locale, calendar, style, period);
         }
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Intl/DateTimeFormat/DateTimeFormat.prototype.format.js b/Userland/Libraries/LibJS/Tests/builtins/Intl/DateTimeFormat/DateTimeFormat.prototype.format.js
index 5a3d9a94b3..709a5d7331 100644
--- a/Userland/Libraries/LibJS/Tests/builtins/Intl/DateTimeFormat/DateTimeFormat.prototype.format.js
+++ b/Userland/Libraries/LibJS/Tests/builtins/Intl/DateTimeFormat/DateTimeFormat.prototype.format.js
@@ -263,11 +263,15 @@ describe("dayPeriod", () => {
     });
 
     test("flexible day period rolls over midnight", () => {
-        // For the en locale, this time (05:00) falls in the flexible day period range of [21:00, 06:00).
-        const date = Date.UTC(2017, 11, 12, 5, 0, 0, 0);
-
         const en = new Intl.DateTimeFormat("en", { dayPeriod: "short", timeZone: "UTC" });
-        expect(en.format(date)).toBe("5 at night");
+
+        // For the en locale, these times (05:00 and 23:00) fall in the flexible day period range of
+        // [21:00, 06:00), on either side of midnight.
+        const date1 = Date.UTC(2017, 11, 12, 5, 0, 0, 0);
+        const date2 = Date.UTC(2017, 11, 12, 23, 0, 0, 0);
+
+        expect(en.format(date1)).toBe("5 at night");
+        expect(en.format(date2)).toBe("11 at night");
     });
 });