diff --git a/test/resources/bootstrap.php b/test/resources/bootstrap.php
index c34420b..e6c58c1 100644
--- a/test/resources/bootstrap.php
+++ b/test/resources/bootstrap.php
@@ -16,7 +16,7 @@
     define('RESOURCES_DIR', ROOT_PATH . '/resources');
 }
 if (!defined('TMPDIR')) {
-    define('TMPDIR', getenv('TMPDIR'));
+    define('TMPDIR', '/tmp');
 }
 require_once implode(DIRECTORY_SEPARATOR, array(
   __DIR__, "..", "..", "vendor", "autoload.php"