diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 496c3880..05e49eda 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -11,3 +11,5 @@
 
 $loader = require __DIR__ . "/../vendor/autoload.php";
 $loader->add('Monolog\\', __DIR__);
+
+date_default_timezone_set('UTC');