diff --git a/src/Responses/Steam/ItemListings.php b/src/Responses/Steam/ItemListings.php
index 079d76d..7354f49 100644
--- a/src/Responses/Steam/ItemListings.php
+++ b/src/Responses/Steam/ItemListings.php
@@ -116,7 +116,7 @@ private function completeListing($data, $listingId, $value): array
     {
         $listingData = [];
 
-        $listingData['listing_id'] = $listingId;
+        $listingData['listing_id'] = (string) $listingId;
         $listingData['asset'] = ResponseService::getAssetData($data['assets'], $value['asset']);
 
         $listingData['original_price_data'] = self::setEmptyPriceData();