diff --git a/_test/tests/inc/mailer.test.php b/_test/tests/inc/mailer.test.php
index 50d282864d89c964373c77a96d49aca347d51d9f..24c5de931dfd7f3b4d15bad026e4201d7b0cd20d 100644
--- a/_test/tests/inc/mailer.test.php
+++ b/_test/tests/inc/mailer.test.php
@@ -190,7 +190,7 @@ class mailer_test extends DokuWikiTest {
 
         // ask message lint if it is okay
         $html = new HTTPClient();
-        $results = $html->post('http://tools.ietf.org/tools/msglint/msglint', array('msg'=>$msg));
+        $results = $html->post('https://tools.ietf.org/tools/msglint/msglint', array('msg'=>$msg));
         if($results === false) {
             $this->markTestSkipped('no response from validator');
             return;