diff --git a/webform.install b/webform.install
index bc0fb83..e8894ce 100644
--- a/webform.install
+++ b/webform.install
@@ -451,6 +451,11 @@
   variable_del('webform_csv_delimiter');
   variable_del('webform_allowed_tags');
   variable_del('webform_blocks');
+  variable_del('webform_search_index');
+  variable_del('webform_email_address_format');
+  variable_del('webform_export_format');
+  variable_del('webform_submission_access_control');
+  variable_del('webform_update_batch_size');
 
   $component_list = array();
   $path = drupal_get_path('module', 'webform') . '/components';