uncaught PDO exception when enabling a menu link

Wehn I enabled a module such as 'Forum' is creates a disabled menu link in the Navigation menu. If I go to the menu module Ui and try to enabled the link, I get a fatal uncaught PDO excpetion:

PDOException: UPDATE {menu_links} SET menu_name=:db_update_placeholder_0, plid=:db_update_placeholder_1, link_path=:db_update_placeholder_2, router_path=:db_update_placeholder_3, hidden=:db_update_placeholder_4, external=:db_update_placeholder_5, has_children=:db_update_placeholder_6, expanded=:db_update_placeholder_7, weight=:db_update_placeholder_8, depth=:db_update_placeholder_9, p1=:db_update_placeholder_10, p2=:db_update_placeholder_11, p3=:db_update_placeholder_12, p4=:db_update_placeholder_13, p5=:db_update_placeholder_14, p6=:db_update_placeholder_15, p7=:db_update_placeholder_16, p8=:db_update_placeholder_17, p9=:db_update_placeholder_18, module=:db_update_placeholder_19, link_title=:db_update_placeholder_20, options=:db_update_placeholder_21, customized=:db_update_placeholder_22 WHERE (mlid = :db_condition_placeholder_12) - Array ( [:db_update_placeholder_0] => navigation [:db_update_placeholder_1] => 0 [:db_update_placeholder_2] => book [:db_update_placeholder_3] => book [:db_update_placeholder_4] => [:db_update_placeholder_5] => 0 [:db_update_placeholder_6] => 0 [:db_update_placeholder_7] => 0 [:db_update_placeholder_8] => 0 [:db_update_placeholder_9] => 1 [:db_update_placeholder_10] => 139 [:db_update_placeholder_11] => 0 [:db_update_placeholder_12] => 0 [:db_update_placeholder_13] => 0 [:db_update_placeholder_14] => 0 [:db_update_placeholder_15] => 0 [:db_update_placeholder_16] => 0 [:db_update_placeholder_17] => 0 [:db_update_placeholder_18] => 0 [:db_update_placeholder_19] => system [:db_update_placeholder_20] => Books [:db_update_placeholder_21] => a:0:{} [:db_update_placeholder_22] => 1 [:db_condition_placeholder_12] => 139 ) SQLSTATE[HY000]: General error: 1366 Incorrect integer value: '' for column 'hidden' at row 1 in menu_link_save() (line 2199 of /Users/Shared/www/drupal-7/includes/menu.inc).

This is obviously because we did away with the automatic casting using the %d placeholder (oh,so sad). So, we need to be sure to cast to int all values going into int columns that might contain non-int values.