diff --git a/src/lib/es2021.intl.d.ts b/src/lib/es2021.intl.d.ts
index a13626aad04..5da7dbddc0e 100644
--- a/src/lib/es2021.intl.d.ts
+++ b/src/lib/es2021.intl.d.ts
@@ -8,9 +8,13 @@ declare namespace Intl {
         fractionalSecondDigits?: 0 | 1 | 2 | 3 | undefined;
     }
 
+    interface DateTimeRangeFormatPart extends DateTimeFormatPart {
+        source: "startRange" | "endRange" | "shared"
+    }
+
     interface DateTimeFormat {
         formatRange(startDate: Date | number | bigint, endDate: Date | number | bigint): string;
-        formatRangeToParts(startDate: Date | number | bigint, endDate: Date | number | bigint): DateTimeFormatPart[];
+        formatRangeToParts(startDate: Date | number | bigint, endDate: Date | number | bigint): DateTimeRangeFormatPart[];
     }
 
     interface ResolvedDateTimeFormatOptions {
diff --git a/src/lib/esnext.intl.d.ts b/src/lib/esnext.intl.d.ts
index a8baa0e4cc6..3c5a0bd4df9 100644
--- a/src/lib/esnext.intl.d.ts
+++ b/src/lib/esnext.intl.d.ts
@@ -1,6 +1,10 @@
 declare namespace Intl {
+  interface NumberRangeFormatPart extends NumberFormatPart {
+    source: "startRange" | "endRange" | "shared"
+  }
+
   interface NumberFormat {
     formatRange(start: number | bigint, end: number | bigint): string;
-    formatRangeToParts(start: number | bigint, end: number | bigint): NumberFormatPart[];
+    formatRangeToParts(start: number | bigint, end: number | bigint): NumberRangeFormatPart[];
   }
 }
diff --git a/tests/baselines/reference/DateTimeFormatAndNumberFormatES2021.types b/tests/baselines/reference/DateTimeFormatAndNumberFormatES2021.types
index 98f06e294c4..4c3c8e654ec 100644
--- a/tests/baselines/reference/DateTimeFormatAndNumberFormatES2021.types
+++ b/tests/baselines/reference/DateTimeFormatAndNumberFormatES2021.types
@@ -42,10 +42,10 @@ new Intl.DateTimeFormat().formatRange
 >formatRange : (startDate: number | bigint | Date, endDate: number | bigint | Date) => string
 
 new Intl.DateTimeFormat().formatRangeToParts
->new Intl.DateTimeFormat().formatRangeToParts : (startDate: number | bigint | Date, endDate: number | bigint | Date) => Intl.DateTimeFormatPart[]
+>new Intl.DateTimeFormat().formatRangeToParts : (startDate: number | bigint | Date, endDate: number | bigint | Date) => Intl.DateTimeRangeFormatPart[]
 >new Intl.DateTimeFormat() : Intl.DateTimeFormat
 >Intl.DateTimeFormat : { (locales?: string | string[], options?: Intl.DateTimeFormatOptions): Intl.DateTimeFormat; new (locales?: string | string[], options?: Intl.DateTimeFormatOptions): Intl.DateTimeFormat; supportedLocalesOf(locales: string | string[], options?: Intl.DateTimeFormatOptions): string[]; readonly prototype: Intl.DateTimeFormat; }
 >Intl : typeof Intl
 >DateTimeFormat : { (locales?: string | string[], options?: Intl.DateTimeFormatOptions): Intl.DateTimeFormat; new (locales?: string | string[], options?: Intl.DateTimeFormatOptions): Intl.DateTimeFormat; supportedLocalesOf(locales: string | string[], options?: Intl.DateTimeFormatOptions): string[]; readonly prototype: Intl.DateTimeFormat; }
->formatRangeToParts : (startDate: number | bigint | Date, endDate: number | bigint | Date) => Intl.DateTimeFormatPart[]
+>formatRangeToParts : (startDate: number | bigint | Date, endDate: number | bigint | Date) => Intl.DateTimeRangeFormatPart[]