diff --git a/src/helpers.js b/src/helpers.js
index 28f0e87..cc360c9 100644
--- a/src/helpers.js
+++ b/src/helpers.js
@@ -69,6 +69,15 @@ export function removeTags(html) {
   return html;
 }
 
+export function shuffle(array) {
+  // Fisher-Yates shuffle
+  for (let i = array.length - 1; i > 0; i--) {
+    const j = Math.floor(Math.random() * (i + 1));
+    [array[i], array[j]] = [array[j], array[i]];
+  }
+  return array;
+}
+
 export function slugify(string) {
   return removeDiacritics(string).replace(/[^a-zA-Z0-9-_]/g, '-');
 }
diff --git a/src/js/ads.js b/src/js/ads.js
index 8ad52cc..7306431 100644
--- a/src/js/ads.js
+++ b/src/js/ads.js
@@ -1,10 +1,10 @@
 import { DISPLAY_AD_EVERY } from '../constants.js';
 import ads from '../../ads.json';
+import { shuffle } from '../helpers.js';
 
 export function setupAds() {
-  const shuffle = (a, b) => Math.random() > 0.5 ? 1 : -1;
-  const priority = ads.filter(ad => isActive(ad) && ad.isPriority).sort(shuffle);
-  const regular = ads.filter(ad => isActive(ad) && !ad.isPriority).sort(shuffle);
+  const priority = shuffle(ads.filter(ad => isActive(ad) && ad.isPriority));
+  const regular = shuffle(ads.filter(ad => isActive(ad) && !ad.isPriority));
   window.ads = [...priority, ...regular];
 }