diff --git a/phpunit.xml b/phpunit.xml
index bb9c4a7e..9ee3e734 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -27,5 +27,6 @@
         <env name="CACHE_DRIVER" value="array"/>
         <env name="SESSION_DRIVER" value="array"/>
         <env name="QUEUE_DRIVER" value="sync"/>
+        <env name="MAIL_DRIVER" value="array"/>
     </php>
 </phpunit>