=== modified file 'modules/filter/filter.install'
--- modules/filter/filter.install	2010-10-20 06:32:32 +0000
+++ modules/filter/filter.install	2010-10-23 00:20:34 +0000
@@ -16,7 +16,7 @@ function filter_schema() {
       'format' => array(
         'type' => 'varchar',
         'length' => 255,
-        'not null' => FALSE,
+        'not null' => TRUE,
         'description' => 'Foreign key: The {filter_format}.format to which this filter is assigned.',
       ),
       'module' => array(