diff --git a/lib/private/User/Manager.php b/lib/private/User/Manager.php
index 822ece3aa94d..84f09111297f 100644
--- a/lib/private/User/Manager.php
+++ b/lib/private/User/Manager.php
@@ -274,6 +274,7 @@ public function searchDisplayName($pattern, $limit = null, $offset = null) {
 	 */
 	public function createUser($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 _\.@\-\']/', $uid)) {
@@ -288,6 +289,12 @@ public function createUser($uid, $password) {
 		if (strlen(trim($uid, "\t\n\r\0\x0B\xe2\x80\x8b")) !== strlen(trim($uid))) {
 			throw new \Exception($l->t('Username contains whitespace at the beginning or at the end'));
 		}
+
+		// Username must be at least 3 characters long
+		if(strlen($uid) < 3) {
+			throw new \Exception($l->t('The username must be at least 3 characters long'));
+		}
+
 		// No empty password
 		if (trim($password) == '') {
 			throw new \Exception($l->t('A valid password must be provided'));