diff --git a/local-moodleappbehat/tests/behat/behat_app_helper.php b/local-moodleappbehat/tests/behat/behat_app_helper.php
index 3a3d07bdf..b2fff6892 100644
--- a/local-moodleappbehat/tests/behat/behat_app_helper.php
+++ b/local-moodleappbehat/tests/behat/behat_app_helper.php
@@ -512,9 +512,9 @@ class behat_app_helper extends behat_base {
 
         // Generate custom URL.
         $parsed_url = parse_url($CFG->behat_wwwroot);
-        $domain = $parsed_url['host'];
-        $rootpath = $parsed_url['path'];
-        $url = $this->get_mobile_url_scheme() . "://$username@$domain/$rootpath?token=$token&privatetoken=$privatetoken";
+        $domain = $parsed_url['host'] ?? '';
+        $rootpath = $parsed_url['path'] ?? '';
+        $url = $this->get_mobile_url_scheme() . "://$username@$domain$rootpath?token=$token&privatetoken=$privatetoken";
 
         if (!empty($path)) {
             $url .= '&redirect='.urlencode($CFG->behat_wwwroot.$path);