diff --git a/swh/loader/debian/tasks.py b/swh/loader/debian/tasks.py
index 6f48012..f61b02f 100644
--- a/swh/loader/debian/tasks.py
+++ b/swh/loader/debian/tasks.py
@@ -1,122 +1,122 @@
 # Copyright (C) 2015  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
 import glob
 import os
 import shutil
 import tempfile
 
 import dateutil
 
 from swh.core.config import load_named_config
 from swh.core.scheduling import Task
 from swh.storage import get_storage
 
 from .listers.snapshot import SnapshotDebianOrg
 from .loader import (
     process_source_packages, try_flush_partial, flush_occurrences,
     flush_release, flush_revision)
 
 
 DEFAULT_CONFIG = {
     'snapshot_connstr': ('str', 'service=snapshot'),
     'snapshot_basedir': ('str', '/home/ndandrim/tmp/snapshot.d.o'),
     'storage_class': ('str', 'local_storage'),
-    'storage_args': ('list', [
+    'storage_args': ('list[str]', [
         'dbname=softwareheritage-dev',
         '/tmp/swh-loader-debian/objects',
     ]),
     'content_packet_size': ('int', 10000),
     'content_packet_length': ('int', 1024 ** 3),
     'content_max_length_one': ('int', 100 * 1024**2),
     'directory_packet_size': ('int', 25000),
-    'keyrings': ('list', glob.glob('/usr/share/keyrings/*')),
+    'keyrings': ('list[str]', glob.glob('/usr/share/keyrings/*')),
 }
 
 
 class LoadSnapshotPackages(Task):
     task_queue = 'swh_loader_debian'
 
     @property
     def config(self):
         if not hasattr(self, '__config'):
             self.__config = load_named_config(
                 'loader/debian.ini',
                 DEFAULT_CONFIG,
             )
         return self.__config
 
     def run(self, *package_names):
         """Load the history of the given package from snapshot.debian.org"""
 
         snapshot = SnapshotDebianOrg(
             connstr=self.config['snapshot_connstr'],
             basedir=self.config['snapshot_basedir'],
         )
 
         storage = get_storage(
             self.config['storage_class'],
             self.config['storage_args'],
         )
 
         swh_authority_dt = open(
             os.path.join(self.config['snapshot_basedir'], 'TIMESTAMP')
         ).read()
 
         swh_authority = {
             'authority': '5f4d4c51-498a-4e28-88b3-b3e4e8396cba',
             'validity': dateutil.parser.parse(swh_authority_dt),
         }
 
         tmpdir = tempfile.mkdtemp()
         os.makedirs(os.path.join(tmpdir, 'source'))
 
         pkgs = snapshot.prepare_packages(
             package_names,
             os.path.join(tmpdir, 'source'),
             log=self.log,
         )
         origins = snapshot.prepare_origins(package_names, storage)
 
         sorted_pkgs = []
         for p in pkgs.values():
             p['origin_id'] = origins[p['name']]['id']
             sorted_pkgs.append(p)
 
         sorted_pkgs.sort(key=lambda p: (p['name'], p['version']))
 
         partial = {}
         for partial in process_source_packages(
                 sorted_pkgs,
                 self.config['keyrings'],
                 tmpdir,
                 log=self.log,
         ):
 
             try_flush_partial(
                 storage, partial,
                 content_packet_size=self.config['content_packet_size'],
                 content_packet_length=self.config['content_packet_length'],
                 content_max_length_one=self.config['content_max_length_one'],
                 directory_packet_size=self.config['directory_packet_size'],
                 log=self.log,
             )
 
         if partial:
             try_flush_partial(
                 storage, partial,
                 content_packet_size=self.config['content_packet_size'],
                 content_packet_length=self.config['content_packet_length'],
                 content_max_length_one=self.config['content_max_length_one'],
                 directory_packet_size=self.config['directory_packet_size'],
                 force=True,
                 log=self.log,
             )
 
             packages = flush_revision(storage, partial, log=self.log)
             packages_w_revisions = flush_release(storage, packages)
             flush_occurrences(storage, packages_w_revisions, [swh_authority])
 
         shutil.rmtree(tmpdir)