diff --git a/ghost/admin/app/services/members-stats.js b/ghost/admin/app/services/members-stats.js
index 550d104f7b..710e40b05d 100644
--- a/ghost/admin/app/services/members-stats.js
+++ b/ghost/admin/app/services/members-stats.js
@@ -4,6 +4,8 @@ import {inject as service} from '@ember/service';
 import {task} from 'ember-concurrency-decorators';
 import {tracked} from '@glimmer/tracking';
 
+const ONE_MINUTE = 1 * 60 * 1000;
+
 export default class MembersStatsService extends Service {
     @service ajax;
     @service ghostPaths;
@@ -18,7 +20,7 @@ export default class MembersStatsService extends Service {
 
     fetch() {
         let daysChanged = this._lastFetchedDays !== this.days;
-        let staleData = this._lastFetched && this._lastFetched - new Date() > 1 * 60 * 1000;
+        let staleData = this._lastFetched && (new Date() - this._lastFetched) > ONE_MINUTE;
 
         // return an already in-progress promise unless params have changed
         if (this._fetchTask.isRunning && !this._forceRefresh && !daysChanged) {
@@ -34,7 +36,7 @@ export default class MembersStatsService extends Service {
     }
 
     fetchTimeline(options = {}) {
-        let staleData = this._lastFetchedTimeline && this._lastFetchedTimeline - new Date() > 1 * 60 * 1000;
+        let staleData = this._lastFetchedTimeline && (new Date() - this._lastFetchedTimeline) > ONE_MINUTE;
         let differentLimit = this._lastFetchedTimelineLimit && this._lastFetchedTimelineLimit !== options.limit;
 
         if (this._fetchTimelineTask.isRunning) {
@@ -49,7 +51,7 @@ export default class MembersStatsService extends Service {
     }
 
     fetchCounts() {
-        let staleData = this._lastFetchedCounts && this._lastFetchedCounts - new Date() > 1 * 60 * 1000;
+        let staleData = this._lastFetchedCounts && (new Date() - this._lastFetchedCounts) > ONE_MINUTE;
 
         // return an already in-progress promise unless params have changed
         if (this._fetchCountsTask.isRunning) {
@@ -65,7 +67,7 @@ export default class MembersStatsService extends Service {
     }
 
     fetchNewsletterStats() {
-        let staleData = this._lastFetchedNewsletterStats && this._lastFetchedNewsletterStats - new Date() > 1 * 60 * 1000;
+        let staleData = this._lastFetchedNewsletterStats && (new Date() - this._lastFetchedNewsletterStats) > ONE_MINUTE;
 
         // return an already in-progress promise unless params have changed
         if (this._fetchNewsletterStatsTask.isRunning) {
@@ -127,7 +129,7 @@ export default class MembersStatsService extends Service {
     }
 
     fetchMRR() {
-        let staleData = this._lastFetchedMRR && this._lastFetchedMRR - new Date() > 1 * 60 * 1000;
+        let staleData = this._lastFetchedMRR && (new Date() - this._lastFetchedMRR) > ONE_MINUTE;
 
         // return an already in-progress promise unless params have changed
         if (this._fetchMRRTask.isRunning) {