diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 2f16bac..786bef2 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -1,6 +1,7 @@
 <?php
 
 error_reporting(E_ALL | E_STRICT);
+date_default_timezone_set('UTC');
 
 // Ensure that composer has installed all dependencies
 if (!file_exists(dirname(__DIR__) . '/vendor/autoload.php')) {