diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/Calendar.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/Calendar.cpp
index 5039a197f08..c3987699761 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/Calendar.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/Calendar.cpp
@@ -503,16 +503,19 @@ ThrowCompletionOr<PlainMonthDay*> calendar_month_day_from_fields(VM& vm, Object&
 }
 
 // 12.2.26 MaybeFormatCalendarAnnotation ( calendarObject, showCalendar ), https://tc39.es/proposal-temporal/#sec-temporal-maybeformatcalendarannotation
-ThrowCompletionOr<String> maybe_format_calendar_annotation(VM& vm, Value calendar_object, StringView show_calendar)
+ThrowCompletionOr<String> maybe_format_calendar_annotation(VM& vm, Object const* calendar_object, StringView show_calendar)
 {
     // 1. If showCalendar is "never", return the empty String.
     if (show_calendar == "never"sv)
         return String::empty();
 
-    // 2. Let calendarID be ? ToString(calendarObject).
-    auto calendar_id = TRY(calendar_object.to_string(vm));
+    // 2. Assert: Type(calendarObject) is Object.
+    VERIFY(calendar_object);
 
-    // 3. Return FormatCalendarAnnotation(calendarID, showCalendar).
+    // 3. Let calendarID be ? ToString(calendarObject).
+    auto calendar_id = TRY(Value(calendar_object).to_string(vm));
+
+    // 4. Return FormatCalendarAnnotation(calendarID, showCalendar).
     return format_calendar_annotation(calendar_id, show_calendar);
 }
 
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/Calendar.h b/Userland/Libraries/LibJS/Runtime/Temporal/Calendar.h
index e176c8d5163..50b98e59364 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/Calendar.h
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/Calendar.h
@@ -59,7 +59,7 @@ ThrowCompletionOr<Object*> get_temporal_calendar_with_iso_default(VM&, Object&);
 ThrowCompletionOr<PlainDate*> calendar_date_from_fields(VM&, Object& calendar, Object const& fields, Object const* options = nullptr);
 ThrowCompletionOr<PlainYearMonth*> calendar_year_month_from_fields(VM&, Object& calendar, Object const& fields, Object const* options = nullptr);
 ThrowCompletionOr<PlainMonthDay*> calendar_month_day_from_fields(VM&, Object& calendar, Object const& fields, Object const* options = nullptr);
-ThrowCompletionOr<String> maybe_format_calendar_annotation(VM&, Value calendar_object, StringView show_calendar);
+ThrowCompletionOr<String> maybe_format_calendar_annotation(VM&, Object const* calendar_object, StringView show_calendar);
 String format_calendar_annotation(StringView id, StringView show_calendar);
 ThrowCompletionOr<bool> calendar_equals(VM&, Object& one, Object& two);
 ThrowCompletionOr<Object*> consolidate_calendars(VM&, Object& one, Object& two);
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/Instant.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/Instant.cpp
index b404177453b..8e1dece2328 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/Instant.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/Instant.cpp
@@ -249,7 +249,7 @@ ThrowCompletionOr<String> temporal_instant_to_string(VM& vm, Instant& instant, V
     auto* date_time = TRY(builtin_time_zone_get_plain_date_time_for(vm, output_time_zone, instant, *iso_calendar));
 
     // 7. Let dateTimeString be ? TemporalDateTimeToString(dateTime.[[ISOYear]], dateTime.[[ISOMonth]], dateTime.[[ISODay]], dateTime.[[ISOHour]], dateTime.[[ISOMinute]], dateTime.[[ISOSecond]], dateTime.[[ISOMillisecond]], dateTime.[[ISOMicrosecond]], dateTime.[[ISONanosecond]], undefined, precision, "never").
-    auto date_time_string = TRY(temporal_date_time_to_string(vm, date_time->iso_year(), date_time->iso_month(), date_time->iso_day(), date_time->iso_hour(), date_time->iso_minute(), date_time->iso_second(), date_time->iso_millisecond(), date_time->iso_microsecond(), date_time->iso_nanosecond(), js_undefined(), precision, "never"sv));
+    auto date_time_string = TRY(temporal_date_time_to_string(vm, date_time->iso_year(), date_time->iso_month(), date_time->iso_day(), date_time->iso_hour(), date_time->iso_minute(), date_time->iso_second(), date_time->iso_millisecond(), date_time->iso_microsecond(), date_time->iso_nanosecond(), nullptr, precision, "never"sv));
 
     String time_zone_string;
 
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateTime.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateTime.cpp
index 91d6be9a3b5..245a319f3f1 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateTime.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateTime.cpp
@@ -268,7 +268,7 @@ ThrowCompletionOr<PlainDateTime*> create_temporal_date_time(VM& vm, i32 iso_year
 }
 
 // 5.5.7 TemporalDateTimeToString ( isoYear, isoMonth, isoDay, hour, minute, second, millisecond, microsecond, nanosecond, calendar, precision, showCalendar ), https://tc39.es/proposal-temporal/#sec-temporal-temporaldatetimetostring
-ThrowCompletionOr<String> temporal_date_time_to_string(VM& vm, i32 iso_year, u8 iso_month, u8 iso_day, u8 hour, u8 minute, u8 second, u16 millisecond, u16 microsecond, u16 nanosecond, Value calendar, Variant<StringView, u8> const& precision, StringView show_calendar)
+ThrowCompletionOr<String> temporal_date_time_to_string(VM& vm, i32 iso_year, u8 iso_month, u8 iso_day, u8 hour, u8 minute, u8 second, u16 millisecond, u16 microsecond, u16 nanosecond, Object const* calendar, Variant<StringView, u8> const& precision, StringView show_calendar)
 {
     // 1. Assert: isoYear, isoMonth, isoDay, hour, minute, second, millisecond, microsecond, and nanosecond are integers.
 
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateTime.h b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateTime.h
index 1192724d2b8..208ddc35073 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateTime.h
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateTime.h
@@ -69,7 +69,7 @@ ThrowCompletionOr<ISODateTime> interpret_temporal_date_time_fields(VM&, Object&
 ThrowCompletionOr<PlainDateTime*> to_temporal_date_time(VM&, Value item, Object const* options = nullptr);
 ISODateTime balance_iso_date_time(i32 year, u8 month, u8 day, u8 hour, u8 minute, u8 second, u16 millisecond, u16 microsecond, i64 nanosecond);
 ThrowCompletionOr<PlainDateTime*> create_temporal_date_time(VM&, i32 iso_year, u8 iso_month, u8 iso_day, u8 hour, u8 minute, u8 second, u16 millisecond, u16 microsecond, u16 nanosecond, Object& calendar, FunctionObject const* new_target = nullptr);
-ThrowCompletionOr<String> temporal_date_time_to_string(VM&, i32 iso_year, u8 iso_month, u8 iso_day, u8 hour, u8 minute, u8 second, u16 millisecond, u16 microsecond, u16 nanosecond, Value calendar, Variant<StringView, u8> const& precision, StringView show_calendar);
+ThrowCompletionOr<String> temporal_date_time_to_string(VM&, i32 iso_year, u8 iso_month, u8 iso_day, u8 hour, u8 minute, u8 second, u16 millisecond, u16 microsecond, u16 nanosecond, Object const* calendar, Variant<StringView, u8> const& precision, StringView show_calendar);
 i8 compare_iso_date_time(i32 year1, u8 month1, u8 day1, u8 hour1, u8 minute1, u8 second1, u16 millisecond1, u16 microsecond1, u16 nanosecond1, i32 year2, u8 month2, u8 day2, u8 hour2, u8 minute2, u8 second2, u16 millisecond2, u16 microsecond2, u16 nanosecond2);
 ThrowCompletionOr<TemporalPlainDateTime> add_date_time(VM&, i32 year, u8 month, u8 day, u8 hour, u8 minute, u8 second, u16 millisecond, u16 microsecond, u16 nanosecond, Object& calendar, double years, double months, double weeks, double days, double hours, double minutes, double seconds, double milliseconds, double microseconds, double nanoseconds, Object* options);
 ISODateTime round_iso_date_time(VM&, i32 year, u8 month, u8 day, u8 hour, u8 minute, u8 second, u16 millisecond, u16 microsecond, u16 nanosecond, u64 increment, StringView unit, StringView rounding_mode, Optional<double> day_length = {});