diff --git a/tests/phpunit/includes/testcase-canonical.php b/tests/phpunit/includes/testcase-canonical.php
index ef33ca8db8..833df23e5b 100644
--- a/tests/phpunit/includes/testcase-canonical.php
+++ b/tests/phpunit/includes/testcase-canonical.php
@@ -1,6 +1,6 @@
 <?php
 
-class WP_Canonical_UnitTestCase extends WP_UnitTestCase {
+abstract class WP_Canonical_UnitTestCase extends WP_UnitTestCase {
 	public static $old_current_user;
 	public static $author_id;
 	public static $post_ids    = array();
diff --git a/tests/phpunit/includes/testcase-xmlrpc.php b/tests/phpunit/includes/testcase-xmlrpc.php
index 7ae8d10e62..8e8026b5c9 100644
--- a/tests/phpunit/includes/testcase-xmlrpc.php
+++ b/tests/phpunit/includes/testcase-xmlrpc.php
@@ -3,7 +3,7 @@ require_once ABSPATH . 'wp-admin/includes/admin.php';
 require_once ABSPATH . WPINC . '/class-IXR.php';
 require_once ABSPATH . WPINC . '/class-wp-xmlrpc-server.php';
 
-class WP_XMLRPC_UnitTestCase extends WP_UnitTestCase {
+abstract class WP_XMLRPC_UnitTestCase extends WP_UnitTestCase {
 	protected $myxmlrpcserver;
 
 	function set_up() {