diff --git a/server/utils/nunjucksSetup.test.ts b/server/utils/nunjucksSetup.test.ts
index 8023d614..36bb7125 100644
--- a/server/utils/nunjucksSetup.test.ts
+++ b/server/utils/nunjucksSetup.test.ts
@@ -131,7 +131,7 @@ describe('Nunjucks Filters', () => {
       jest.useRealTimers()
     })
     ;[
-      { input: '2025-11-15', expected: '' }, // erroneous future date of birth
+      { input: '3025-11-15', expected: '' }, // future date of birth
       { input: '2020-11-15', expected: '0 months old' },
       { input: '2020-11-14', expected: '1 month old' },
       { input: '2020-10-15', expected: '1 month old' },
diff --git a/server/utils/nunjucksSetup.ts b/server/utils/nunjucksSetup.ts
index ab529677..f0727b9b 100644
--- a/server/utils/nunjucksSetup.ts
+++ b/server/utils/nunjucksSetup.ts
@@ -93,22 +93,14 @@ export function registerNunjucks(app?: express.Express): Environment {
       return ''
     }
 
-    const emptyDuration = {
-      years: 0,
-      months: 0,
-      days: 0,
-      hours: 0,
-      minutes: 0,
-      seconds: 0,
-    }
-    const intervalDuration = intervalToDuration({ start: dob, end: today })
-    const duration = { ...emptyDuration, ...intervalDuration }
+    const duration = intervalToDuration({ start: dob, end: today })
 
     let age = ''
-    if (duration.years < 1) {
-      age = formatDuration(duration, { format: ['months'], zero: true })
-    } else {
+    if (duration.years) {
       age = formatDuration(duration, { format: ['years'] })
+    } else {
+      // workaround below for Duration zero/undefined change (https://github.com/date-fns/date-fns/issues/3658)
+      age = formatDuration(duration, { format: ['months'] }) || '0 months'
     }
 
     return `${age} old`