diff --git a/htdocs/resource/element_resource.php b/htdocs/resource/element_resource.php
index 4d44c1f6564ad..9fb6e826e6082 100644
--- a/htdocs/resource/element_resource.php
+++ b/htdocs/resource/element_resource.php
@@ -203,7 +203,7 @@
 
 				// removing the rows associated with our action id
 				$ac_id = (int) $object->element_id;
-				$busyResources = array_filter($_busyResources, function ($row) : bool {
+				$busyResources = array_filter($_busyResources, function (Dolresource $row) : bool {
 					global $ac_id;
 					return $row->ac_id != $ac_id;
 				});