diff --git a/tests/phpunit/includes/mock-mailer.php b/tests/phpunit/includes/mock-mailer.php
index cae2cbc655..edc36b9ec6 100644
--- a/tests/phpunit/includes/mock-mailer.php
+++ b/tests/phpunit/includes/mock-mailer.php
@@ -1,6 +1,6 @@
 <?php
-require_once ABSPATH . '/wp-includes/PHPMailer/PHPMailer.php';
-require_once ABSPATH . '/wp-includes/PHPMailer/Exception.php';
+require_once ABSPATH . 'wp-includes/PHPMailer/PHPMailer.php';
+require_once ABSPATH . 'wp-includes/PHPMailer/Exception.php';
 
 class MockPHPMailer extends PHPMailer\PHPMailer\PHPMailer {
 	var $mock_sent = array();