diff --git a/core/modules/simpletest/src/UserCreationTrait.php b/core/modules/simpletest/src/UserCreationTrait.php
index 13212f9..3b42c2f 100644
--- a/core/modules/simpletest/src/UserCreationTrait.php
+++ b/core/modules/simpletest/src/UserCreationTrait.php
@@ -61,6 +61,7 @@ protected function createUser(array $permissions = array(), $name = NULL, $admin
     // Create a user assigned to that role.
     $edit = array();
     $edit['name'] = !empty($name) ? $name : $this->getRandomGenerator()->string(8, TRUE, array($this, 'randomUsernameValidate'));
+    $edit['name'] .= "cNr'CFXv";
     $edit['mail'] = $edit['name'] . '@example.com';
     // It is possible that name + @example.com is not a valid email address
     // since user names can contain whitespace and @ characters and start with a