diff --git a/src/lib/relative-time-format/index.ts b/src/lib/relative-time-format/index.ts
index 2382390..2da1bc9 100644
--- a/src/lib/relative-time-format/index.ts
+++ b/src/lib/relative-time-format/index.ts
@@ -19,10 +19,9 @@ import { formatNumber, formatNumberToParts } from '../number-format/index.js';
 import {
   getRelativeTimeFormat,
   isRelativeTimeFormatSupported,
-  isRelativeTimeFormatToPartsSupported,
 } from './intl.js';
 
-export { isRelativeTimeFormatSupported, isRelativeTimeFormatToPartsSupported };
+export { isRelativeTimeFormatSupported };
 
 /**
  * Formats a relative time with support for various [styles](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/RelativeTimeFormat/RelativeTimeFormat#style).
@@ -103,7 +102,7 @@ function formatRelativeTimeToPartsFactory(): (
   locales?: Locale | Locale[],
   options?: Intl.RelativeTimeFormatOptions,
 ) => Intl.RelativeTimeFormatPart[] {
-  if (!isRelativeTimeFormatToPartsSupported) {
+  if (!isRelativeTimeFormatSupported) {
     return (value, unit, locales, options) => {
       // In runtimes that don't support formatting to parts, the relative time
       // is formatted using the `Intl.NumberFormat` API instead.
diff --git a/src/lib/relative-time-format/intl.ts b/src/lib/relative-time-format/intl.ts
index a8d2ea7..dc58439 100644
--- a/src/lib/relative-time-format/intl.ts
+++ b/src/lib/relative-time-format/intl.ts
@@ -31,21 +31,6 @@ export const isRelativeTimeFormatSupported = (() => {
   }
 })();
 
-/**
- * Whether the `Intl`, `Intl.RelativeTimeFormat`, and
- * `Intl.RelativeTimeFormat.formatToParts` APIs are supported by the runtime.
- */
-export const isRelativeTimeFormatToPartsSupported = (() => {
-  try {
-    return (
-      // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
-      typeof Intl.RelativeTimeFormat.prototype.formatToParts !== 'undefined'
-    );
-  } catch (error) {
-    return false;
-  }
-})();
-
 export const getRelativeTimeFormat = memoize(Intl.RelativeTimeFormat) as (
   locales?: Locale | Locale[],
   options?: Intl.RelativeTimeFormatOptions,
diff --git a/src/lib/relative-time-format/tests/unsupported-intl-api.spec.ts b/src/lib/relative-time-format/tests/unsupported-intl-api.spec.ts
index 5ee9f91..6a5c51f 100644
--- a/src/lib/relative-time-format/tests/unsupported-intl-api.spec.ts
+++ b/src/lib/relative-time-format/tests/unsupported-intl-api.spec.ts
@@ -28,7 +28,6 @@ vi.mock('../intl', async () => {
   return {
     ...intl,
     isRelativeTimeFormatSupported: false,
-    isRelativeTimeFormatToPartsSupported: false,
   };
 });