diff --git a/Services/LDAP/classes/class.ilLDAPQuery.php b/Services/LDAP/classes/class.ilLDAPQuery.php
index c77b347344e6..3e5f6a0dd941 100644
--- a/Services/LDAP/classes/class.ilLDAPQuery.php
+++ b/Services/LDAP/classes/class.ilLDAPQuery.php
@@ -511,7 +511,7 @@ private function readUserData(string $a_name, bool $a_check_dn = false, bool $a_
      * @param array|null $controls LDAP Control to be passed on the the ldap functions
      * @return resource|null
      */
-    private function queryByScope(int $a_scope, string $a_base_dn, string $a_filter, array $a_attributes, array $controls = null)
+    private function queryByScope(int $a_scope, string $a_base_dn, string $a_filter, array $a_attributes, array $controls = [])
     {
         $a_filter = $a_filter ?: "(objectclass=*)";