diff --git a/core/modules/taxonomy/taxonomy.install b/core/modules/taxonomy/taxonomy.install
index 4ad0773..d8cc9eb 100644
--- a/core/modules/taxonomy/taxonomy.install
+++ b/core/modules/taxonomy/taxonomy.install
@@ -85,8 +85,8 @@ function taxonomy_schema() {
       'uuid' => array('uuid'),
     ),
     'indexes' => array(
-      'taxonomy_tree' => array('vid', 'weight', 'name'),
-      'vid_name' => array('vid', 'name'),
+      'taxonomy_tree' => array(array('vid', 64), 'weight', 'name'),
+      'vid_name' => array(array('vid', 64), 'name'),
       'name' => array('name'),
     ),
   );