pg_query() error after upgrade from Webform 6.x-2.10

I'm getting following error while accessing Drupal Blocks panel:

    * warning: pg_query() [function.pg-query]: Query failed: ERROR: operator does not exist: character varying = integer LINE 1: ... node n ON w.nid = n.nid WHERE w.block = 1 AND n.type IN (0) ^ HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts. in /usr/share/drupal6/includes/database.pgsql.inc on line 139.
    * user warning: query: SELECT n.title, n.nid FROM webform w LEFT JOIN node n ON w.nid = n.nid WHERE w.block = 1 AND n.type IN (0) in /etc/drupal/6/sites/all/modules/webform/webform.module on line 1385.

The problem seems to be in $placeholders = db_placeholders($webform_node_types) assigment.
Changing it to $placeholders = db_placeholders($webform_node_types, 'varchar') solves it.