diff --git a/inc/target_actor.class.php b/inc/target_actor.class.php
index 6e67e977c..8036d04cf 100644
--- a/inc/target_actor.class.php
+++ b/inc/target_actor.class.php
@@ -236,7 +236,7 @@ public function export($remove_uuid = false) {
    public function deleteObsoleteItems(CommonDBTM $container, array $exclude)
    {
       $keepCriteria = [
-         self::$items_id => $container->getID(),
+         static::$items_id => $container->getID(),
       ];
       if (count($exclude) > 0) {
          $keepCriteria[] = ['NOT' => ['id' => $exclude]];
diff --git a/inc/targetbase.class.php b/inc/targetbase.class.php
index e3aed16b6..094b169b3 100644
--- a/inc/targetbase.class.php
+++ b/inc/targetbase.class.php
@@ -1821,7 +1821,7 @@ protected function showActorSettingsForType($actorType, array $actors) {
    public function deleteObsoleteItems(CommonDBTM $container, array $exclude)
    {
       $keepCriteria = [
-         self::$items_id => $container->getID(),
+         static::$items_id => $container->getID(),
       ];
       if (count($exclude) > 0) {
          $keepCriteria[] = ['NOT' => ['id' => $exclude]];