diff --git a/modules/nativoBidAdapter.js b/modules/nativoBidAdapter.js
index 9b7ffef8957..06586b80102 100644
--- a/modules/nativoBidAdapter.js
+++ b/modules/nativoBidAdapter.js
@@ -98,7 +98,11 @@ export const spec = {
     ]
 
     if (placementIds.size > 0) {
-      params.unshift({ key: 'ntv_ptd', value: placementIds.toString() })
+      // Convert Set to Array (IE 11 Safe)
+      const placements = []
+      placementIds.forEach((value) => placements.push(value))
+      // Append to query string paramters
+      params.unshift({ key: 'ntv_ptd', value: placements.join(',') })
     }
 
     if (bidderRequest.gdprConsent) {