block does not get deleted if using custom machine name

If I set a custom machine name for the nodeblock it does not get deleted when the node gets deleted. This is due to node delete hook not taking into account the machine name. It tries to delete the block by the default delta (nid) eg:

db_delete('block')
        ->condition('module', 'nodeblock')
        ->condition('delta', $node->nid)
        ->execute();