Index: modules/node/node.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/node/node.module,v
retrieving revision 1.776.2.1
diff -u -p -r1.776.2.1 node.module
--- modules/node/node.module	29 Jan 2007 21:51:53 -0000	1.776.2.1
+++ modules/node/node.module	23 Feb 2007 01:54:54 -0000
@@ -1987,7 +1987,9 @@ function node_form($node, $form_values =
   $form['changed'] = array('#type' => 'hidden', '#default_value' => $node->changed);
 
   // Get the node-specific bits.
-  $form = array_merge_recursive($form, node_invoke($node, 'form', $form_values));
+  if ($extra = node_invoke($node, 'form', $form_values)) {
+    $form = array_merge_recursive($form, $extra);
+  }
   if (!isset($form['title']['#weight'])) {
     $form['title']['#weight'] = -5;
   }