diff --git a/enrol/category/locallib.php b/enrol/category/locallib.php
index f9231955dd8..6a7671b7dbd 100644
--- a/enrol/category/locallib.php
+++ b/enrol/category/locallib.php
@@ -33,7 +33,7 @@ defined('MOODLE_INTERNAL') || die();
  * it may fail sometimes, so we always do a full sync in cron too.
  */
 class enrol_category_handler {
-    public function role_assigned($ra) {
+    public static function role_assigned($ra) {
         global $DB;
 
         if (!enrol_is_enabled('category')) {
@@ -84,7 +84,7 @@ class enrol_category_handler {
         return true;
     }
 
-    public function role_unassigned($ra) {
+    public static function role_unassigned($ra) {
         global $DB;
 
         if (!enrol_is_enabled('category')) {
diff --git a/enrol/cohort/locallib.php b/enrol/cohort/locallib.php
index 2a8057bdbe2..5ca237a6c29 100644
--- a/enrol/cohort/locallib.php
+++ b/enrol/cohort/locallib.php
@@ -40,7 +40,7 @@ class enrol_cohort_handler {
      * @param stdClass $ca
      * @return bool
      */
-    public function member_added($ca) {
+    public static function member_added($ca) {
         global $DB;
 
         if (!enrol_is_enabled('cohort')) {
@@ -79,7 +79,7 @@ class enrol_cohort_handler {
      * @param stdClass $ca
      * @return bool
      */
-    public function member_removed($ca) {
+    public static function member_removed($ca) {
         global $DB;
 
         // does anything want to sync with this cohort?
@@ -114,7 +114,7 @@ class enrol_cohort_handler {
      * @param stdClass $cohort
      * @return bool
      */
-    public function deleted($cohort) {
+    public static function deleted($cohort) {
         global $DB;
 
         // does anything want to sync with this cohort?