diff --git a/tests/phpunit/tests/ms.php b/tests/phpunit/tests/ms.php
index 185133d1e6..b2ad547243 100644
--- a/tests/phpunit/tests/ms.php
+++ b/tests/phpunit/tests/ms.php
@@ -1510,7 +1510,7 @@ class Tests_MS extends WP_UnitTestCase {
 	 * @param string $path   REQUEST_URI of the boot strap request.
 	 */
 	function _setup_host_request( $domain, $path ) {
-		global $current_site, $current_blog, $table_prefix;
+		global $current_site, $current_blog, $table_prefix, $wpdb;
 
 		$table_prefix = WP_TESTS_TABLE_PREFIX;
 		$current_site = $current_blog = null;