diff --git a/classes/restriction/info.php b/classes/restriction/info.php
index 73ecc7f4..1028a00b 100644
--- a/classes/restriction/info.php
+++ b/classes/restriction/info.php
@@ -159,12 +159,12 @@ public function get_course_module() {
      *   required for all course-modules, to make the front page and similar
      *   pages work more quickly (works only for current user)
      * @param int $userid If set, specifies a different user ID to check availability for
-     * @param \course_modinfo $modinfo Usually leave as null for default. Specify when
+     * @param \course_modinfo|null $modinfo Usually leave as null for default. Specify when
      *   calling recursively from inside get_fast_modinfo()
      * @return bool True if this item is available to the user, false otherwise
      */
     public function is_available(&$information, $grabthelot = false, $userid = 0,
-            \course_modinfo $modinfo = null) {
+            \course_modinfo|null $modinfo = null) {
         global $USER, $OUTPUT, $DB;
 
         // Default to no information.
diff --git a/lib.php b/lib.php
index 6847092e..f495832d 100644
--- a/lib.php
+++ b/lib.php
@@ -402,7 +402,7 @@ public function can_add_instance($courseid) {
      * @param bool $charge Charge the user to enrol (only false in case of enrol coupons)
      * @return bool|array true if enrolled else error code and message
      */
-    public function enrol_self(stdClass $instance, \stdClass $user = null, $charge = true) {
+    public function enrol_self(stdClass $instance, \stdClass|null $user = null, $charge = true) {
         global $CFG, $DB, $USER;
         require_once("$CFG->dirroot/enrol/wallet/locallib.php");
         if (empty($user)) {
@@ -1893,10 +1893,10 @@ public function get_possible_currencies($account = null) {
     /**
      * Add new instance of enrol plugin.
      * @param object $course
-     * @param array $fields instance fields
+     * @param array|null $fields instance fields
      * @return int id of new instance, null if can not be created
      */
-    public function add_instance($course, array $fields = null) {
+    public function add_instance($course, array|null $fields = null) {
 
         offers::parse_data($fields);