diff --git a/src/Clients/VoucherList.php b/src/Clients/VoucherList.php
index 3e6fed3..5184b72 100644
--- a/src/Clients/VoucherList.php
+++ b/src/Clients/VoucherList.php
@@ -70,7 +70,7 @@ public function setToEverything(): self
 
     protected function buildQueryParams(array $params): string
     {
-        $dateFormat = DateTimeInterface::ATOM;
+        $dateFormat = 'Y-m-d';
 
         $params['voucherType'] = implode(',', $this->types);
         $params['voucherStatus'] = implode(',', $this->statuses);