diff --git a/domain_taxonomy.module b/domain_taxonomy.module
index c78a9a2..f371b5d 100644
--- a/domain_taxonomy.module
+++ b/domain_taxonomy.module
@@ -98,6 +98,10 @@ function domain_taxonomy_form_alter(&$form, &$form_state, $form_id) {
   // Apply to all term editing forms
   if (in_array($form['#id'], array('taxonomy-form-term', 'forum-form-forum', 'forum-form-container'))) {
     $term = taxonomy_term_load($form['tid']['#value']);
+    
+    if (!isset($form['vid']))
+      return;
+    
     $vocabulary = taxonomy_vocabulary_load($form['vid']['#value']);
 
     $disabled_vocs = _domain_taxonomy_get_disabled_vocabulares();