diff --git a/app/javascript/mastodon/utils/time.test.ts b/app/javascript/mastodon/utils/time.test.ts
index add0c7d3cd9..fffcd6f5a18 100644
--- a/app/javascript/mastodon/utils/time.test.ts
+++ b/app/javascript/mastodon/utils/time.test.ts
@@ -1,4 +1,13 @@
-import { DAY, HOUR, MINUTE, relativeTimeParts, SECOND } from './time';
+import { createIntl } from 'react-intl';
+
+import {
+  DAY,
+  HOUR,
+  MINUTE,
+  SECOND,
+  relativeTimeParts,
+  formatTime,
+} from './time';
 
 describe('relativeTimeParts', () => {
   const now = Date.now();
@@ -36,3 +45,19 @@ describe('relativeTimeParts', () => {
     expect(relativeTimeParts(now + input, now)).toMatchObject(expected);
   });
 });
+
+describe('formatTime with day-only timestamps', () => {
+  const intl = createIntl({ locale: 'en' });
+
+  const now = Date.parse('2026-08-20T22:56:00Z');
+
+  test.concurrent.each([
+    ['2026-08-20', 'today'],
+    ['2026-08-19', '1 day ago'],
+    ['2026-08-17', '3 days ago'],
+  ])('should format the day-only value %s as "%s"', (date, expected) => {
+    expect(
+      formatTime({ timestamp: Date.parse(date), intl, now, noTime: true }),
+    ).toBe(expected);
+  });
+});
diff --git a/app/javascript/mastodon/utils/time.ts b/app/javascript/mastodon/utils/time.ts
index c2bbdc747f7..d22cf4940d6 100644
--- a/app/javascript/mastodon/utils/time.ts
+++ b/app/javascript/mastodon/utils/time.ts
@@ -41,13 +41,13 @@ export function relativeTimeParts(
   return { value: sign * Math.floor(absDelta / DAY), unit: 'day', delta };
 }
 
-export function isToday(ts: number, now = Date.now()): boolean {
+export function isSameUTCDay(ts: number, now = Date.now()): boolean {
   const date = new Date(ts);
   const nowDate = new Date(now);
   return (
-    date.getDate() === nowDate.getDate() &&
-    date.getMonth() === nowDate.getMonth() &&
-    date.getFullYear() === nowDate.getFullYear()
+    date.getUTCDate() === nowDate.getUTCDate() &&
+    date.getUTCMonth() === nowDate.getUTCMonth() &&
+    date.getUTCFullYear() === nowDate.getUTCFullYear()
   );
 }
 
@@ -138,7 +138,7 @@ export function formatTime({
   const { value, unit } = relativeTimeParts(timestamp, now);
 
   // If we're only showing days, show "today" for the current day.
-  if (noTime && isToday(timestamp, now)) {
+  if (noTime && isSameUTCDay(timestamp, now)) {
     return intl.formatMessage(timeMessages.today);
   }