diff --git a/lib/ads/interstitial_ad_manager.js b/lib/ads/interstitial_ad_manager.js
index 7b2be125c4..b8be920221 100644
--- a/lib/ads/interstitial_ad_manager.js
+++ b/lib/ads/interstitial_ad_manager.js
@@ -948,10 +948,11 @@ shaka.ads.InterstitialAdManager = class {
             }
           }
         }
-        for (const asset of dataAsJson['ASSETS']) {
+        for (let i = 0; i < dataAsJson['ASSETS'].length; i++) {
+          const asset = dataAsJson['ASSETS'][i];
           if (asset['URI']) {
             interstitialsAd.push({
-              id,
+              id: id + '_asset_' + i,
               startTime,
               endTime,
               uri: asset['URI'],