diff --git a/JSTests/stress/intl-datetimeformat.js b/JSTests/stress/intl-datetimeformat.js
index 6bb394e393562..e40ff6026cd9f 100644
--- a/JSTests/stress/intl-datetimeformat.js
+++ b/JSTests/stress/intl-datetimeformat.js
@@ -700,7 +700,7 @@ shouldBe(JSON.stringify(Intl.DateTimeFormat('zh', { era: 'short', year: 'numeric
     {
         let dtf = new Intl.DateTimeFormat("en", {hour: "numeric", minute: "numeric", second: "numeric", fractionalSecondDigits: 1});
         shouldBe(dtf.format(t), `7:00:23.1 AM`);
-        shouldBe(JSON.stringify(dtf.resolvedOptions()), `{"locale":"en","calendar":"gregory","numberingSystem":"latn","timeZone":"America/Los_Angeles","hourCycle":"h12","hour12":true,"dayPeriod":"short","hour":"numeric","minute":"2-digit","second":"2-digit","fractionalSecondDigits":1}`);
+        shouldBe(JSON.stringify(dtf.resolvedOptions()), `{"locale":"en","calendar":"gregory","numberingSystem":"latn","timeZone":"America/Los_Angeles","hourCycle":"h12","hour12":true,"hour":"numeric","minute":"2-digit","second":"2-digit","fractionalSecondDigits":1}`);
     }
     shouldThrow(() => {
         new Intl.DateTimeFormat("en", {hour: "numeric", minute: "numeric", second: "numeric", fractionalSecondDigits: 0});
diff --git a/Source/JavaScriptCore/runtime/IntlDateTimeFormat.cpp b/Source/JavaScriptCore/runtime/IntlDateTimeFormat.cpp
index 48fe494425647..caf284133b680 100644
--- a/Source/JavaScriptCore/runtime/IntlDateTimeFormat.cpp
+++ b/Source/JavaScriptCore/runtime/IntlDateTimeFormat.cpp
@@ -342,6 +342,10 @@ void IntlDateTimeFormat::setFormatsFromPattern(IntlDateTimeFormatImpl& impl, Str
                 impl.m_day = Day::TwoDigit;
             break;
         case 'a':
+            // AM/PM marker. Governed by hourCycle/hour12, not the dayPeriod
+            // option (ECMA-402 Table: Components of date and time formats),
+            // so it does not populate [[DayPeriod]] for resolvedOptions().
+            break;
         case 'b':
         case 'B':
             if (count <= 3)