diff -urp --strip-trailing-cr ../category/category.module ./category.module
--- ../category/category.module	2009-08-05 06:52:53.000000000 +0200
+++ ./category.module	2009-09-20 00:40:47.000000000 +0200
@@ -317,7 +317,7 @@ function category_menu() {
  */
 function category_init() {
   drupal_add_css(drupal_get_path('module', 'category') .'/category.css');
-  require_once dirname(drupal_get_filename('module', 'category')) .'/category.inc';
+  module_load_include('inc', 'category');
 }
 
 /**
@@ -866,6 +866,10 @@ function category_node_type($op, $info) 
  * Handles category loading, inserting and updating.
  */
 function category_nodeapi(&$node, $op, $teaser, $page) {
+  // Ensure that category.inc is loaded. We generally do that in hook_init(),
+  // but some faulty modules might call a node_load() even before that runs.
+  module_load_include('inc', 'category');
+
   switch ($op) {
     case 'load':
       $output = array();