Index: /trunk/roundcubemail/program/include/main.inc
===================================================================
--- /trunk/roundcubemail/program/include/main.inc	(revision 1581)
+++ /trunk/roundcubemail/program/include/main.inc	(revision 1582)
@@ -77,6 +77,7 @@
     {
     $db = &rcmail::get_instance()->db;
-
-    if ($db->db_provider=='pgsql' && is_a($db, 'rcube_mdb2'))
+    $dbclass = 'rcube_mdb2';
+    
+    if ($db->db_provider=='pgsql' && ($db instanceof $dbclass))
       {
       $db->db_handle->setOption('disable_smart_seqname', true);