diff --git a/test/Ebanx/Command/Request/DirectTest.php b/test/Ebanx/Command/Request/DirectTest.php
index b6d3188..2427fac 100644
--- a/test/Ebanx/Command/Request/DirectTest.php
+++ b/test/Ebanx/Command/Request/DirectTest.php
@@ -201,7 +201,7 @@ public function testValidateEmail()
     public function testValidatePaymentTypeCode()
     {
         $this->setExpectedException('InvalidArgumentException', "The parameter 'payment.payment_type_code' was not supplied.");
-        $this->params['payment']['payment_type_code'] = NULL; // weird bug fix, undefined index payment_type_code
+        $this->params['payment']['payment_type_code'] = null; // weird bug fix, undefined index payment_type_code
         \Ebanx\Ebanx::doRequest($this->params);
     }