diff --git a/entity.module b/entity.module
index d4a882c..6e0ad36 100644
--- a/entity.module
+++ b/entity.module
@@ -1557,6 +1557,9 @@ function _entity_info_add_metadata(&$entity_info) {
     $entity_info['taxonomy_term']['token type'] = 'term';
     $entity_info['taxonomy_vocabulary']['token type'] = 'vocabulary';
   }
+
+  // Allow modules to alter any of these values.
+  drupal_alter('entity_info_metadata', $entity_info);
 }
 
 /**