diff --git a/ts/test-node/util/groupSendEndorsements_test.ts b/ts/test-node/util/groupSendEndorsements_test.ts
index 0cd4fbd38..02e543593 100644
--- a/ts/test-node/util/groupSendEndorsements_test.ts
+++ b/ts/test-node/util/groupSendEndorsements_test.ts
@@ -8,8 +8,9 @@ import { DAY, HOUR, SECOND } from '../../util/durations';
 describe('groupSendEndorsements', () => {
   describe('validateGroupSendEndorsementsExpiration', () => {
     function validateDistance(distance: number) {
-      const expiration = Date.now() + distance;
-      return validateGroupSendEndorsementsExpiration(expiration);
+      const now = Date.now();
+      const expiration = now + distance;
+      return validateGroupSendEndorsementsExpiration(expiration, now);
     }
 
     function checkValid(label: string, distance: number) {
diff --git a/ts/util/groupSendEndorsements.ts b/ts/util/groupSendEndorsements.ts
index 57323380a..ae161b31a 100644
--- a/ts/util/groupSendEndorsements.ts
+++ b/ts/util/groupSendEndorsements.ts
@@ -134,10 +134,11 @@ export type ValidationResult =
   | { valid: false; reason: string };
 
 export function validateGroupSendEndorsementsExpiration(
-  expiration: number
+  expiration: number,
+  now: number = Date.now()
 ): ValidationResult {
   const expSeconds = DurationInSeconds.fromMillis(expiration);
-  const nowSeconds = DurationInSeconds.fromMillis(Date.now());
+  const nowSeconds = DurationInSeconds.fromMillis(now);
   const info = `now: ${nowSeconds}, exp: ${expSeconds}`;
   if (expSeconds <= nowSeconds) {
     return { valid: false, reason: `already expired, ${info}` };