diff --git a/core/tests/bootstrap.php b/core/tests/bootstrap.php
index fd980a4..a4af993 100644
--- a/core/tests/bootstrap.php
+++ b/core/tests/bootstrap.php
@@ -88,4 +88,4 @@ function drupal_phpunit_register_extension_dirs(Composer\Autoload\ClassLoader $l
 
 // Set the default timezone. While this doesn't cause any tests to fail, PHP
 // complains if 'date.timezone' is not set in php.ini.
-date_default_timezone_set('UTC');
+date_default_timezone_set('America/Los_Angeles');