diff --git a/swh/loader/mercurial/tasks.py b/swh/loader/mercurial/tasks.py
index 113cd90..b269315 100644
--- a/swh/loader/mercurial/tasks.py
+++ b/swh/loader/mercurial/tasks.py
@@ -1,33 +1,33 @@
 # Copyright (C) 2017-2019  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
 
 from celery import shared_task
 
 from .loader import HgBundle20Loader, HgArchiveBundle20Loader
 
 
 @shared_task(name=__name__ + '.LoadMercurial')
-def load_hg(url, directory=None, visit_date=None):
+def load_hg(*, url, directory=None, visit_date=None):
     """Mercurial repository loading
 
     Import a mercurial tarball into swh.
 
     Args: see :func:`DepositLoader.load`.
 
     """
     loader = HgBundle20Loader(
         url, directory=directory, visit_date=visit_date)
     return loader.load()
 
 
 @shared_task(name=__name__ + '.LoadArchiveMercurial')
-def load_hg_from_archive(url, archive_path=None, visit_date=None):
+def load_hg_from_archive(*, url, archive_path=None, visit_date=None):
     """Import a mercurial tarball into swh.
 
     Args: see :func:`DepositLoader.load`.
     """
     loader = HgArchiveBundle20Loader(
         url, archive_path=archive_path, visit_date=visit_date)
     return loader.load()