diff --git a/swh/loader/package/pypi.py b/swh/loader/package/pypi.py
index 9a82f52..18daf82 100644
--- a/swh/loader/package/pypi.py
+++ b/swh/loader/package/pypi.py
@@ -1,191 +1,191 @@
 # Copyright (C) 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
 
 import os
 
 from typing import Generator, Dict, Tuple, Sequence
 from urllib.parse import urlparse
 from pkginfo import UnpackedSDist
 
 import iso8601
 import requests
 
 from swh.model.identifiers import normalize_timestamp
 from swh.loader.package import DEFAULT_PARAMS
 from swh.loader.package.loader import PackageLoader
 from swh.loader.package.utils import download
 
 
 def pypi_api_url(url: str) -> str:
     """Compute api url from a project url
 
     Args:
         url (str): PyPI instance's url (e.g: https://pypi.org/project/requests)
         This deals with correctly transforming the project's api url (e.g
         https://pypi.org/pypi/requests/json)
 
     Returns:
         api url
 
     """
     p_url = urlparse(url)
     project_name = p_url.path.split('/')[-1]
     url = '%s://%s/pypi/%s/json' % (p_url.scheme, p_url.netloc, project_name)
     return url
 
 
 def pypi_info(url: str) -> Dict:
     """PyPI api client to retrieve information on project. This deals with
        fetching json metadata about pypi projects.
 
     Args:
         url (str): PyPI instance's url (e.g: https://pypi.org/project/requests)
         This deals with correctly transforming the project's api url (e.g
         https://pypi.org/pypi/requests/json)
 
     Raises:
         ValueError in case of query failures (for some reasons: 404, ...)
 
     Returns:
         PyPI's information dict
 
     """
     api_url = pypi_api_url(url)
     response = requests.get(api_url, **DEFAULT_PARAMS)
     if response.status_code != 200:
         raise ValueError("Fail to query '%s'. Reason: %s" % (
             api_url, response.status_code))
     return response.json()
 
 
 def sdist_parse(dir_path: str) -> Dict:
     """Given an uncompressed path holding the pkginfo file, returns a
        pkginfo parsed structure as a dict.
 
        The release artifact contains at their root one folder. For example:
        $ tar tvf zprint-0.0.6.tar.gz
        drwxr-xr-x root/root         0 2018-08-22 11:01 zprint-0.0.6/
        ...
 
     Args:
 
         dir_path (str): Path to the uncompressed directory
                         representing a release artifact from pypi.
 
     Returns:
         the pkginfo parsed structure as a dict if any or None if
         none was present.
 
     """
     # Retrieve the root folder of the archive
     if not os.path.exists(dir_path):
         return {}
     lst = os.listdir(dir_path)
-    if len(lst) == 0:
+    if len(lst) != 1:
         return {}
     project_dirname = lst[0]
     pkginfo_path = os.path.join(dir_path, project_dirname, 'PKG-INFO')
     if not os.path.exists(pkginfo_path):
         return {}
     pkginfo = UnpackedSDist(pkginfo_path)
     raw = pkginfo.__dict__
     raw.pop('filename')  # this gets added with the ondisk location
     return raw
 
 
 def author(data: Dict) -> Dict:
     """Given a dict of project/release artifact information (coming from
        PyPI), returns an author subset.
 
     Args:
         data (dict): Representing either artifact information or
                      release information.
 
     Returns:
         swh-model dict representing a person.
 
     """
     name = data.get('author')
     email = data.get('author_email')
 
     if email:
         fullname = '%s <%s>' % (name, email)
     else:
         fullname = name
 
     if not fullname:
         return {'fullname': b'', 'name': None, 'email': None}
 
     fullname = fullname.encode('utf-8')
 
     if name is not None:
         name = name.encode('utf-8')
 
     if email is not None:
         email = email.encode('utf-8')
 
     return {'fullname': fullname, 'name': name, 'email': email}
 
 
 class PyPILoader(PackageLoader):
     """Load pypi origin's artifact releases into swh archive.
 
     """
     visit_type = 'pypi'
 
     def __init__(self, url):
         super().__init__(url=url)
         self._info = None
 
     @property
     def info(self) -> Dict:
         """Return the project metadata information (fetched from pypi registry)
 
         """
         if not self._info:
             self._info = pypi_info(self.url)
         return self._info
 
     def get_versions(self) -> Sequence[str]:
         return self.info['releases'].keys()
 
     def get_default_release(self) -> str:
         return self.info['info']['version']
 
     def get_artifacts(self, version: str) -> Generator[
             Tuple[str, str, Dict], None, None]:
         for meta in self.info['releases'][version]:
             yield meta['filename'], meta['url'], meta
 
     def fetch_artifact_archive(
             self, artifact_uri: str, dest: str) -> Tuple[str, Dict]:
         return download(artifact_uri, dest=dest)
 
     def build_revision(
             self, a_metadata: Dict, a_uncompressed_path: str) -> Dict:
         # Parse metadata (project, artifact metadata)
         metadata = sdist_parse(a_uncompressed_path)
 
         # from intrinsic metadata
         name = metadata['version']
         _author = author(metadata)
 
         # from extrinsic metadata
         message = a_metadata.get('comment_text', '')
         message = '%s: %s' % (name, message) if message else name
         date = normalize_timestamp(
             int(iso8601.parse_date(a_metadata['upload_time']).timestamp()))
 
         return {
             'message': message.encode('utf-8'),
             'author': _author,
             'date': date,
             'committer': _author,
             'committer_date': date,
             'parents': [],
             'metadata': {
                 'intrinsic_metadata': metadata,
             }
         }