diff --git a/webapp/services/callback/GameItemMarketBuyOk.php b/webapp/services/callback/GameItemMarketBuyOk.php
index affa6cc7..2630447a 100644
--- a/webapp/services/callback/GameItemMarketBuyOk.php
+++ b/webapp/services/callback/GameItemMarketBuyOk.php
@@ -22,7 +22,7 @@ class GameItemMarketBuyOk {
     public function process()
     {
         SignatureService::web3ServiceCheck();
-        $buyer = getReqVal('buyer', '');
+        $buyer = strtolower(getReqVal('buyer', ''));
         $orderId = getReqVal('order_id', '');
         $currency = getReqVal('currency', '');
         $price = getReqVal('price', '');