diff --git a/apps/web/src/common/utils/time.test.ts b/apps/web/src/common/utils/time.test.ts
index 8479d4647..ce104d10b 100644
--- a/apps/web/src/common/utils/time.test.ts
+++ b/apps/web/src/common/utils/time.test.ts
@@ -20,4 +20,10 @@ describe('time', () => {
   it('formatToNowStrict', function () {
     expect(formatToNowStrict('2022-09-28T02:11:54Z')).toBe('2 months');
   });
+
+  it('returns an empty string for a value that is not a date', () => {
+    expect(formatISO('not-a-date')).toEqual('');
+    expect(formatToNow('not-a-date')).toEqual('');
+    expect(formatToNowStrict('not-a-date')).toEqual('');
+  });
 });
diff --git a/apps/web/src/common/utils/time.ts b/apps/web/src/common/utils/time.ts
index fce7917ae..5efe299e9 100644
--- a/apps/web/src/common/utils/time.ts
+++ b/apps/web/src/common/utils/time.ts
@@ -1,4 +1,5 @@
 import {
+  isValid,
   formatDistanceToNow,
   formatDistanceToNowStrict,
   format,
@@ -14,18 +15,23 @@ const languages = { en: enGB, zh: zhCN };
 export const formatISO = (s: string, layout?: string) => {
   if (!s) return '';
   const p = parseJSON(s);
+  // date-fns format() throws RangeError on an invalid date; a malformed value in
+  // the series must not take the whole page down.
+  if (!isValid(p)) return '';
   return format(p, layout || FORMAT_YMD);
 };
 
 export const formatToNow = (s: string) => {
   if (!s) return '';
   const p = parseJSON(s);
+  if (!isValid(p)) return '';
   return formatDistanceToNow(p, { locale: languages[local] });
 };
 
 export const formatToNowStrict = (s: string) => {
   if (!s) return '';
   const p = parseJSON(s);
+  if (!isValid(p)) return '';
   return formatDistanceToNowStrict(p, { locale: languages[local] });
 };