diff --git a/include/class.file.php b/include/class.file.php
index bcdb9e0ed68f0ce7a944a9ae866ea5626dd4b90b..2a0073b4be2817ecbd41e28858e1487184fffba4 100644
--- a/include/class.file.php
+++ b/include/class.file.php
@@ -635,7 +635,7 @@ class AttachmentFile extends VerySimpleModel {
             ->filter(array(
                 'attachments__object_id__isnull' => true,
                 'ft' => 'T',
-                'created__gt' => new DateTime('now -1 day'),
+                'created__lt' => SqlFunction::NOW()->minus(SqlInterval::DAY(1)),
             ));
 
         foreach ($files as $f) {