diff --git a/src/Illuminate/Notifications/Messages/MailMessage.php b/src/Illuminate/Notifications/Messages/MailMessage.php
index f40f9c216e3e..ec67001d2580 100644
--- a/src/Illuminate/Notifications/Messages/MailMessage.php
+++ b/src/Illuminate/Notifications/Messages/MailMessage.php
@@ -314,6 +314,7 @@ public function render()
 
         return Container::getInstance()
             ->make(Markdown::class)
+            ->theme($this->theme ?: 'default')
             ->render($this->markdown, $this->data());
     }