diff --git a/modules/forum/forum.module b/modules/forum/forum.module
index 1b027f3..7867f36 100644
--- a/modules/forum/forum.module
+++ b/modules/forum/forum.module
@@ -216,8 +216,7 @@ function forum_nodeapi(&$node, $op, $teaser = NULL, $page = NULL) {
     case 'prepare':
       if (empty($node->nid)) {
         // New topic
-        $node->taxonomy[arg(3)]->vid = $vid;
-        $node->taxonomy[arg(3)]->tid = arg(3);
+        $node->taxonomy[arg(3)] = (object) array('vid' => $vid, 'tid' => arg(3));
       }
       break;