diff --git a/lib/private/user/manager.php b/lib/private/user/manager.php
index b547f98161..86750dcd99 100644
--- a/lib/private/user/manager.php
+++ b/lib/private/user/manager.php
@@ -256,10 +256,10 @@ class Manager extends PublicEmitter implements IUserManager {
 	public function createUser($uid, $password) {
 		$l = \OC::$server->getL10N('lib');
 		// Check the name for bad characters
-		// Allowed are: "a-z", "A-Z", "0-9" and "_.@-"
-		if (preg_match('/[^a-zA-Z0-9 _\.@\-]/', $uid)) {
+		// Allowed are: "a-z", "A-Z", "0-9" and "_.@-'"
+		if (preg_match('/[^a-zA-Z0-9 _\.@\-\']/', $uid)) {
 			throw new \Exception($l->t('Only the following characters are allowed in a username:'
-				. ' "a-z", "A-Z", "0-9", and "_.@-"'));
+				. ' "a-z", "A-Z", "0-9", and "_.@-\'"'));
 		}
 		// No empty username
 		if (trim($uid) == '') {