--- knurl.install	2007-12-18 17:45:07.000000000 -0500
+++ knurl.install	2009-04-03 18:58:59.000000000 -0400
@@ -31,7 +31,8 @@
         'type' => 'text',
         'not null' => TRUE,
         'default' => '') 
-      ) /*!40100 DEFAULT CHARACTER SET UTF8 */ 
+        ), /*!40100 DEFAULT CHARACTER SET UTF8 */
+      'primary key' => array('tid'),
   );
   return $schema;
 }