diff --git a/tests/phpunit/includes/testcase.php b/tests/phpunit/includes/testcase.php
index 5f77db201f..345c7492d0 100644
--- a/tests/phpunit/includes/testcase.php
+++ b/tests/phpunit/includes/testcase.php
@@ -37,6 +37,7 @@ class WP_UnitTestCase extends PHPUnit_Framework_TestCase {
 		$wpdb->query( 'ROLLBACK' );
 		$wp_query = new WP_Query();
 		$post = null;
+		remove_theme_support( 'html5' );
 		remove_filter( 'query', array( $this, '_create_temporary_tables' ) );
 		remove_filter( 'query', array( $this, '_drop_temporary_tables' ) );
 		remove_filter( 'wp_die_handler', array( $this, 'get_wp_die_handler' ) );