diff --git a/modules/proxistoreBidAdapter.js b/modules/proxistoreBidAdapter.js
index 32e6daf3096..f9c3a0f3cc0 100644
--- a/modules/proxistoreBidAdapter.js
+++ b/modules/proxistoreBidAdapter.js
@@ -9,7 +9,7 @@ function _mapSizes(sizes) {
 
 function _createServerRequest(bidRequests, bidderRequest) {
   const payload = {
-    bidId: bidRequests.map(req => req.bidId)[0],
+    bidId: bidRequests.map(req => req.bidId),
     auctionId: bidRequests[0].auctionId,
     transactionId: bidRequests[0].transactionId,
     sizes: _mapSizes(bidRequests.map(x => x.sizes)),