diff --git a/swh/loader/package/npm/loader.py b/swh/loader/package/npm/loader.py
index d9065eb..fe015d6 100644
--- a/swh/loader/package/npm/loader.py
+++ b/swh/loader/package/npm/loader.py
@@ -1,278 +1,280 @@
 # 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 json
 import logging
 import os
 
 from codecs import BOM_UTF8
 from typing import Any, Dict, Generator, Mapping, Sequence, Tuple, Optional
 
 import chardet
 import iso8601
 
 from urllib.parse import quote
 from swh.model.identifiers import normalize_timestamp
 from swh.loader.package.loader import PackageLoader
 from swh.loader.package.utils import (
     api_info, release_name, parse_author, swh_author
 )
 
 
 logger = logging.getLogger(__name__)
 
 
 class NpmLoader(PackageLoader):
     """Load npm origin's artifact releases into swh archive.
 
     """
     visit_type = 'npm'
 
     def __init__(self, url: str):
         """Constructor
 
         Args
             str: origin url (e.g. https://www.npmjs.com/package/<package-name>)
         """
         super().__init__(url=url)
         package_name = url.split('https://www.npmjs.com/package/')[1]
         safe_name = quote(package_name, safe='')
         self.provider_url = f'https://replicate.npmjs.com/{safe_name}/'
         self._info: Dict[str, Any] = {}
         self._versions = None
 
     @property
     def info(self) -> Dict[str, Any]:
         """Return the project metadata information (fetched from npm registry)
 
         """
         if not self._info:
             self._info = api_info(self.provider_url)
         return self._info
 
     def get_versions(self) -> Sequence[str]:
         return sorted(list(self.info['versions'].keys()))
 
     def get_default_version(self) -> str:
         return self.info['dist-tags'].get('latest', '')
 
     def get_package_info(self, version: str) -> Generator[
             Tuple[str, Mapping[str, Any]], None, None]:
         meta = self.info['versions'][version]
         url = meta['dist']['tarball']
         p_info = {
             'url': url,
             'filename': os.path.basename(url),
             'raw': meta,
         }
         yield release_name(version), p_info
 
     def resolve_revision_from(
             self, known_artifacts: Dict, artifact_metadata: Dict) \
             -> Optional[bytes]:
         return artifact_to_revision_id(known_artifacts, artifact_metadata)
 
     def build_revision(
             self, a_metadata: Dict, uncompressed_path: str) -> Dict:
         i_metadata = extract_intrinsic_metadata(uncompressed_path)
         if not i_metadata:
             return {}
         # from intrinsic metadata
         author = extract_npm_package_author(i_metadata)
         message = i_metadata['version'].encode('ascii')
 
         # from extrinsic metadata
 
         # No date available in intrinsic metadata: retrieve it from the API
         # metadata, using the version number that the API claims this package
         # has.
         extrinsic_version = a_metadata['version']
 
         if 'time' in self.info:
             date = self.info['time'][extrinsic_version]
+        elif 'mtime' in a_metadata:
+            date = a_metadata['mtime']
         else:
             artifact_name = os.path.basename(a_metadata['dist']['tarball'])
             raise ValueError(
                 'Origin %s: Cannot determine upload time for artifact %s.' %
                 (self.url, artifact_name)
             )
 
         date = iso8601.parse_date(date)
         date = normalize_timestamp(int(date.timestamp()))
 
         return {
             'type': 'tar',
             'message': message,
             'author': author,
             'date': date,
             'committer': author,
             'committer_date': date,
             'parents': [],
             'metadata': {
                 'intrinsic': {
                     'tool': 'package.json',
                     'raw': i_metadata,
                 },
                 'extrinsic': {
                     'provider': self.provider_url,
                     'when': self.visit_date.isoformat(),
                     'raw': a_metadata,
                 },
             },
         }
 
 
 def artifact_to_revision_id(
         known_artifacts: Dict, artifact_metadata: Dict) -> Optional[bytes]:
     """Given metadata artifact, solves the associated revision id.
 
     The following code allows to deal with 2 metadata formats:
 
     - old format sample::
 
         {
             'package_source': {
                 'sha1': '05181c12cd8c22035dd31155656826b85745da37',
             }
         }
 
     - new format sample::
 
         {
             'original_artifact': [{
                 'checksums': {
                     'sha256': '6975816f2c5ad4046acc676ba112f2fff945b01522d63948531f11f11e0892ec', # noqa
                     ...
                 },
             }],
             ...
         }
 
     """
     shasum = artifact_metadata['dist']['shasum']
     for rev_id, known_artifact in known_artifacts.items():
         known_original_artifact = known_artifact.get('original_artifact')
         if not known_original_artifact:
             # previous loader-npm version kept original artifact elsewhere
             known_original_artifact = known_artifact.get('package_source')
             if not known_original_artifact:
                 continue
             original_hash = known_original_artifact['sha1']
         else:
             assert isinstance(known_original_artifact, list)
             original_hash = known_original_artifact[0]['checksums']['sha1']
         if shasum == original_hash:
             return rev_id
     return None
 
 
 def extract_npm_package_author(package_json):
     """
     Extract package author from a ``package.json`` file content and
     return it in swh format.
 
     Args:
         package_json (dict): Dict holding the content of parsed
             ``package.json`` file
 
     Returns:
         dict: A dict with the following keys:
             * fullname
             * name
             * email
 
     """
 
     def _author_str(author_data):
         if type(author_data) is dict:
             author_str = ''
             if 'name' in author_data:
                 author_str += author_data['name']
             if 'email' in author_data:
                 author_str += ' <%s>' % author_data['email']
             return author_str
         elif type(author_data) is list:
             return _author_str(author_data[0]) if len(author_data) > 0 else ''
         else:
             return author_data
 
     author_data = {}
     for author_key in ('author', 'authors'):
         if author_key in package_json:
             author_str = _author_str(package_json[author_key])
             author_data = parse_author(author_str)
 
     return swh_author(author_data)
 
 
 def _lstrip_bom(s, bom=BOM_UTF8):
     if s.startswith(bom):
         return s[len(bom):]
     else:
         return s
 
 
 def load_json(json_bytes):
     """
     Try to load JSON from bytes and return a dictionary.
 
     First try to decode from utf-8. If the decoding failed,
     try to detect the encoding and decode again with replace
     error handling.
 
     If JSON is malformed, an empty dictionary will be returned.
 
     Args:
         json_bytes (bytes): binary content of a JSON file
 
     Returns:
         dict: JSON data loaded in a dictionary
     """
     json_data = {}
     try:
         json_str = _lstrip_bom(json_bytes).decode('utf-8')
     except UnicodeDecodeError:
         encoding = chardet.detect(json_bytes)['encoding']
         if encoding:
             json_str = json_bytes.decode(encoding, 'replace')
     try:
         json_data = json.loads(json_str)
     except json.decoder.JSONDecodeError:
         pass
     return json_data
 
 
 def extract_intrinsic_metadata(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 npm.
 
     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:
         return {}
     project_dirname = lst[0]
     package_json_path = os.path.join(dir_path, project_dirname, 'package.json')
     if not os.path.exists(package_json_path):
         return {}
     with open(package_json_path, 'rb') as package_json_file:
         package_json_bytes = package_json_file.read()
         return load_json(package_json_bytes)
diff --git a/swh/loader/package/npm/tests/data/https_registry.npmjs.org/jammit-express_-_jammit-express-0.0.1.tgz b/swh/loader/package/npm/tests/data/https_registry.npmjs.org/jammit-express_-_jammit-express-0.0.1.tgz
new file mode 100644
index 0000000..9a8788e
Binary files /dev/null and b/swh/loader/package/npm/tests/data/https_registry.npmjs.org/jammit-express_-_jammit-express-0.0.1.tgz differ
diff --git a/swh/loader/package/npm/tests/data/https_replicate.npmjs.com/jammit-express b/swh/loader/package/npm/tests/data/https_replicate.npmjs.com/jammit-express
new file mode 100644
index 0000000..c0df681
--- /dev/null
+++ b/swh/loader/package/npm/tests/data/https_replicate.npmjs.com/jammit-express
@@ -0,0 +1,80 @@
+{
+  "_id": "jammit-express",
+  "_rev": "1-ffa3f96992e5e31dd29df779dc771e84",
+  "name": "jammit-express",
+  "description": "Jammit Helpers for Express.js",
+  "dist-tags": {
+    "latest": "0.0.1"
+  },
+  "versions": {
+    "0.0.1": {
+      "name": "jammit-express",
+      "version": "0.0.1",
+      "description": "Jammit Helpers for Express.js",
+      "author": {
+        "name": "Eric Abouaf",
+        "email": "eric.abouaf@mail.com"
+      },
+      "bugs": {
+        "web": "http://github.com/neyric/jammit-express/issues"
+      },
+      "os": [
+        "darwin",
+        "linux"
+      ],
+      "contributors": [
+        {
+          "name": "Eric Abouaf",
+          "email": "eric.abouaf@mail.com",
+          "url": "http://neyric.com"
+        }
+      ],
+      "engines": {
+        "node": ">=0.2.0"
+      },
+      "directories": {
+        "lib": "lib"
+      },
+      "main": "./init",
+      "bin": null,
+      "dependencies": null,
+      "licenses": [
+        {
+          "type": "BSD"
+        }
+      ],
+      "repository": {
+        "type": "git",
+        "url": "http://github.com/neyric/jammit-express.git"
+      },
+      "_id": "jammit-express@0.0.1",
+      "_nodeSupported": true,
+      "_npmVersion": "0.2.7-2",
+      "_nodeVersion": "v0.3.1-pre",
+      "dist": {
+        "tarball": "https://registry.npmjs.org/jammit-express/-/jammit-express-0.0.1.tgz",
+        "shasum": "10927257f0512af082200a91e24d9ec9cccedbba"
+      },
+      "mtime": "2010-11-09T23:27:28Z",
+      "ctime": "2010-11-09T23:27:28Z"
+    }
+  },
+  "maintainers": [
+    {
+      "name": "neyric",
+      "email": "eric.abouaf@mail.com"
+    }
+  ],
+  "mtime": "2010-11-09T23:27:28Z",
+  "ctime": "2010-11-09T23:27:28Z",
+  "author": {
+    "name": "Eric Abouaf",
+    "email": "eric.abouaf@mail.com"
+  },
+  "repository": {
+    "type": "git",
+    "url": "http://github.com/neyric/jammit-express.git"
+  },
+  "readme": "",
+  "readmeFilename": ""
+}
diff --git a/swh/loader/package/npm/tests/test_npm.py b/swh/loader/package/npm/tests/test_npm.py
index 1e1bcb6..7a5010a 100644
--- a/swh/loader/package/npm/tests/test_npm.py
+++ b/swh/loader/package/npm/tests/test_npm.py
@@ -1,558 +1,590 @@
 # 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 json
 import os
 import pytest
 
 from swh.model.hashutil import hash_to_bytes
 
 from swh.loader.package.npm.loader import (
     NpmLoader, extract_npm_package_author,
     artifact_to_revision_id
 )
 from swh.loader.package.tests.common import (
     check_snapshot, check_metadata_paths, get_stats
 )
 
 
 def test_extract_npm_package_author(datadir):
     package_metadata_filepath = os.path.join(
         datadir, 'https_replicate.npmjs.com', 'org_visit1')
 
     with open(package_metadata_filepath) as json_file:
         package_metadata = json.load(json_file)
 
     extract_npm_package_author(package_metadata['versions']['0.0.2']) == \
         {
             'fullname': b'mooz <stillpedant@gmail.com>',
             'name': b'mooz',
             'email': b'stillpedant@gmail.com'
         }
 
     assert (
         extract_npm_package_author(package_metadata['versions']['0.0.3']) ==
         {
             'fullname': b'Masafumi Oyamada <stillpedant@gmail.com>',
             'name': b'Masafumi Oyamada',
             'email': b'stillpedant@gmail.com'
         }
     )
 
     package_json = json.loads('''
     {
         "name": "highlightjs-line-numbers.js",
         "version": "2.7.0",
         "description": "Highlight.js line numbers plugin.",
         "main": "src/highlightjs-line-numbers.js",
         "dependencies": {},
         "devDependencies": {
             "gulp": "^4.0.0",
             "gulp-rename": "^1.4.0",
             "gulp-replace": "^0.6.1",
             "gulp-uglify": "^1.2.0"
         },
         "repository": {
             "type": "git",
             "url": "https://github.com/wcoder/highlightjs-line-numbers.js.git"
         },
         "author": "Yauheni Pakala <evgeniy.pakalo@gmail.com>",
         "license": "MIT",
         "bugs": {
             "url": "https://github.com/wcoder/highlightjs-line-numbers.js/issues"
         },
         "homepage": "http://wcoder.github.io/highlightjs-line-numbers.js/"
     }''') # noqa
 
     assert extract_npm_package_author(package_json) == \
         {
             'fullname': b'Yauheni Pakala <evgeniy.pakalo@gmail.com>',
             'name': b'Yauheni Pakala',
             'email': b'evgeniy.pakalo@gmail.com'
         }
 
     package_json = json.loads('''
     {
         "name": "3-way-diff",
         "version": "0.0.1",
         "description": "3-way diffing of JavaScript objects",
         "main": "index.js",
         "authors": [
             {
                 "name": "Shawn Walsh",
                 "url": "https://github.com/shawnpwalsh"
             },
             {
                 "name": "Markham F Rollins IV",
                 "url": "https://github.com/mrollinsiv"
             }
         ],
         "keywords": [
             "3-way diff",
             "3 way diff",
             "three-way diff",
             "three way diff"
         ],
         "devDependencies": {
             "babel-core": "^6.20.0",
             "babel-preset-es2015": "^6.18.0",
             "mocha": "^3.0.2"
         },
         "dependencies": {
             "lodash": "^4.15.0"
         }
     }''')
 
     assert extract_npm_package_author(package_json) == \
         {
             'fullname': b'Shawn Walsh',
             'name': b'Shawn Walsh',
             'email': None
         }
 
     package_json = json.loads('''
     {
         "name": "yfe-ynpm",
         "version": "1.0.0",
         "homepage": "http://gitlab.ywwl.com/yfe/yfe-ynpm",
         "repository": {
             "type": "git",
             "url": "git@gitlab.ywwl.com:yfe/yfe-ynpm.git"
         },
         "author": [
             "fengmk2 <fengmk2@gmail.com> (https://fengmk2.com)",
             "xufuzi <xufuzi@ywwl.com> (https://7993.org)"
         ],
         "license": "MIT"
     }''')
 
     assert extract_npm_package_author(package_json) == \
         {
             'fullname': b'fengmk2 <fengmk2@gmail.com>',
             'name': b'fengmk2',
             'email': b'fengmk2@gmail.com'
         }
 
     package_json = json.loads('''
     {
         "name": "umi-plugin-whale",
         "version": "0.0.8",
         "description": "Internal contract component",
         "authors": {
             "name": "xiaohuoni",
             "email": "448627663@qq.com"
         },
         "repository": "alitajs/whale",
         "devDependencies": {
             "np": "^3.0.4",
             "umi-tools": "*"
         },
         "license": "MIT"
     }''')
 
     assert extract_npm_package_author(package_json) == \
         {
             'fullname': b'xiaohuoni <448627663@qq.com>',
             'name': b'xiaohuoni',
             'email': b'448627663@qq.com'
         }
 
 
 def normalize_hashes(hashes):
     if isinstance(hashes, str):
         return hash_to_bytes(hashes)
     if isinstance(hashes, list):
         return [hash_to_bytes(x) for x in hashes]
     return {hash_to_bytes(k): hash_to_bytes(v) for k, v in hashes.items()}
 
 
 _expected_new_contents_first_visit = normalize_hashes([
     '4ce3058e16ab3d7e077f65aabf855c34895bf17c',
     '858c3ceee84c8311adc808f8cdb30d233ddc9d18',
     '0fa33b4f5a4e0496da6843a38ff1af8b61541996',
     '85a410f8ef8eb8920f2c384a9555566ad4a2e21b',
     '9163ac8025923d5a45aaac482262893955c9b37b',
     '692cf623b8dd2c5df2c2998fd95ae4ec99882fb4',
     '18c03aac6d3e910efb20039c15d70ab5e0297101',
     '41265c42446aac17ca769e67d1704f99e5a1394d',
     '783ff33f5882813dca9239452c4a7cadd4dba778',
     'b029cfb85107aee4590c2434a3329bfcf36f8fa1',
     '112d1900b4c2e3e9351050d1b542c9744f9793f3',
     '5439bbc4bd9a996f1a38244e6892b71850bc98fd',
     'd83097a2f994b503185adf4e719d154123150159',
     'd0939b4898e83090ee55fd9d8a60e312cfadfbaf',
     'b3523a26f7147e4af40d9d462adaae6d49eda13e',
     'cd065fb435d6fb204a8871bcd623d0d0e673088c',
     '2854a40855ad839a54f4b08f5cff0cf52fca4399',
     'b8a53bbaac34ebb8c6169d11a4b9f13b05c583fe',
     '0f73d56e1cf480bded8a1ecf20ec6fc53c574713',
     '0d9882b2dfafdce31f4e77fe307d41a44a74cefe',
     '585fc5caab9ead178a327d3660d35851db713df1',
     'e8cd41a48d79101977e3036a87aeb1aac730686f',
     '5414efaef33cceb9f3c9eb5c4cc1682cd62d14f7',
     '9c3cc2763bf9e9e37067d3607302c4776502df98',
     '3649a68410e354c83cd4a38b66bd314de4c8f5c9',
     'e96ed0c091de1ebdf587104eaf63400d1974a1fe',
     '078ca03d2f99e4e6eab16f7b75fbb7afb699c86c',
     '38de737da99514de6559ff163c988198bc91367a',
 ])
 
 _expected_new_directories_first_visit = normalize_hashes([
     '3370d20d6f96dc1c9e50f083e2134881db110f4f',
     '42753c0c2ab00c4501b552ac4671c68f3cf5aece',
     'd7895533ef5edbcffdea3f057d9fef3a1ef845ce',
     '80579be563e2ef3e385226fe7a3f079b377f142c',
     '3b0ddc6a9e58b4b53c222da4e27b280b6cda591c',
     'bcad03ce58ac136f26f000990fc9064e559fe1c0',
     '5fc7e82a1bc72e074665c6078c6d3fad2f13d7ca',
     'e3cd26beba9b1e02f6762ef54bd9ac80cc5f25fd',
     '584b5b4b6cf7f038095e820b99386a9c232de931',
     '184c8d6d0d242f2b1792ef9d3bf396a5434b7f7a',
     'bb5f4ee143c970367eb409f2e4c1104898048b9d',
     '1b95491047add1103db0dfdfa84a9735dcb11e88',
     'a00c6de13471a2d66e64aca140ddb21ef5521e62',
     '5ce6c1cd5cda2d546db513aaad8c72a44c7771e2',
     'c337091e349b6ac10d38a49cdf8c2401ef9bb0f2',
     '202fafcd7c0f8230e89d5496ad7f44ab12b807bf',
     '775cc516543be86c15c1dc172f49c0d4e6e78235',
     'ff3d1ead85a14f891e8b3fa3a89de39db1b8de2e',
 ])
 
 _expected_new_revisions_first_visit = normalize_hashes({
     'd8a1c7474d2956ac598a19f0f27d52f7015f117e':
     '42753c0c2ab00c4501b552ac4671c68f3cf5aece',
     '5f9eb78af37ffd12949f235e86fac04898f9f72a':
     '3370d20d6f96dc1c9e50f083e2134881db110f4f',
     'ba019b192bdb94bd0b5bd68b3a5f92b5acc2239a':
     'd7895533ef5edbcffdea3f057d9fef3a1ef845ce'}
 )
 
 
 def package_url(package):
     return 'https://www.npmjs.com/package/%s' % package
 
 
 def package_metadata_url(package):
     return 'https://replicate.npmjs.com/%s/' % package
 
 
 def test_revision_metadata_structure(swh_config, requests_mock_datadir):
     package = 'org'
     loader = NpmLoader(package_url(package))
 
     actual_load_status = loader.load()
     assert actual_load_status['status'] == 'eventful'
     assert actual_load_status['snapshot_id'] is not None
 
     expected_revision_id = hash_to_bytes(
         'd8a1c7474d2956ac598a19f0f27d52f7015f117e')
     revision = list(loader.storage.revision_get([expected_revision_id]))[0]
 
     assert revision is not None
 
     check_metadata_paths(revision['metadata'], paths=[
         ('intrinsic.tool', str),
         ('intrinsic.raw', dict),
         ('extrinsic.provider', str),
         ('extrinsic.when', str),
         ('extrinsic.raw', dict),
         ('original_artifact', list),
     ])
 
     for original_artifact in revision['metadata']['original_artifact']:
         check_metadata_paths(original_artifact, paths=[
             ('filename', str),
             ('length', int),
             ('checksums', dict),
         ])
 
 
 def test_npm_loader_first_visit(swh_config, requests_mock_datadir):
 
     package = 'org'
     loader = NpmLoader(package_url(package))
 
     actual_load_status = loader.load()
     expected_snapshot_id = 'd0587e1195aed5a8800411a008f2f2d627f18e2d'
     assert actual_load_status == {
         'status': 'eventful',
         'snapshot_id': expected_snapshot_id
     }
 
     stats = get_stats(loader.storage)
 
     assert {
         'content': len(_expected_new_contents_first_visit),
         'directory': len(_expected_new_directories_first_visit),
         'origin': 1,
         'origin_visit': 1,
         'person': 2,
         'release': 0,
         'revision': len(_expected_new_revisions_first_visit),
         'skipped_content': 0,
         'snapshot': 1,
     } == stats
 
     assert len(list(loader.storage.content_get(
         _expected_new_contents_first_visit))) == len(
             _expected_new_contents_first_visit)
 
     assert list(loader.storage.directory_missing(
         _expected_new_directories_first_visit)) == []
 
     assert list(loader.storage.revision_missing(
         _expected_new_revisions_first_visit)) == []
 
     expected_snapshot = {
         'id': expected_snapshot_id,
         'branches': {
             'HEAD': {
                 'target': 'releases/0.0.4',
                 'target_type': 'alias'
             },
             'releases/0.0.2': {
                 'target': 'd8a1c7474d2956ac598a19f0f27d52f7015f117e',
                 'target_type': 'revision'
             },
             'releases/0.0.3': {
                 'target': '5f9eb78af37ffd12949f235e86fac04898f9f72a',
                 'target_type': 'revision'
             },
             'releases/0.0.4': {
                 'target': 'ba019b192bdb94bd0b5bd68b3a5f92b5acc2239a',
                 'target_type': 'revision'
             }
         }
     }
     check_snapshot(expected_snapshot, loader.storage)
 
 
 def test_npm_loader_incremental_visit(
         swh_config, requests_mock_datadir_visits):
     package = 'org'
     url = package_url(package)
     loader = NpmLoader(url)
 
     actual_load_status = loader.load()
     assert actual_load_status['status'] == 'eventful'
     assert actual_load_status['status'] is not None
     origin_visit = list(loader.storage.origin_visit_get(url))[-1]
     assert origin_visit['status'] == 'full'
     assert origin_visit['type'] == 'npm'
 
     stats = get_stats(loader.storage)
 
     assert {
         'content': len(_expected_new_contents_first_visit),
         'directory': len(_expected_new_directories_first_visit),
         'origin': 1,
         'origin_visit': 1,
         'person': 2,
         'release': 0,
         'revision': len(_expected_new_revisions_first_visit),
         'skipped_content': 0,
         'snapshot': 1,
     } == stats
 
     loader._info = None  # reset loader internal state
     actual_load_status2 = loader.load()
     assert actual_load_status2['status'] == 'eventful'
     snap_id2 = actual_load_status2['snapshot_id']
     assert snap_id2 is not None
     assert snap_id2 != actual_load_status['snapshot_id']
 
     origin_visit2 = list(loader.storage.origin_visit_get(url))[-1]
     assert origin_visit2['status'] == 'full'
     assert origin_visit2['type'] == 'npm'
 
     stats = get_stats(loader.storage)
 
     assert {  # 3 new releases artifacts
         'content': len(_expected_new_contents_first_visit) + 14,
         'directory': len(_expected_new_directories_first_visit) + 15,
         'origin': 1,
         'origin_visit': 2,
         'person': 2,
         'release': 0,
         'revision': len(_expected_new_revisions_first_visit) + 3,
         'skipped_content': 0,
         'snapshot': 2,
     } == stats
 
     urls = [
         m.url for m in requests_mock_datadir_visits.request_history
         if m.url.startswith('https://registry.npmjs.org')
     ]
     assert len(urls) == len(set(urls))  # we visited each artifact once across
 
 
 @pytest.mark.usefixtures('requests_mock_datadir')
 def test_npm_loader_version_divergence(swh_config):
     package = '@aller_shared'
     url = package_url(package)
     loader = NpmLoader(url)
 
     actual_load_status = loader.load()
     assert actual_load_status['status'] == 'eventful'
     assert actual_load_status['status'] is not None
     origin_visit = list(loader.storage.origin_visit_get(url))[-1]
     assert origin_visit['status'] == 'full'
     assert origin_visit['type'] == 'npm'
 
     stats = get_stats(loader.storage)
 
     assert {  # 1 new releases artifacts
         'content': 534,
         'directory': 153,
         'origin': 1,
         'origin_visit': 1,
         'person': 1,
         'release': 0,
         'revision': 2,
         'skipped_content': 0,
         'snapshot': 1,
     } == stats
 
     expected_snapshot = {
         'id': 'b11ebac8c9d0c9e5063a2df693a18e3aba4b2f92',
         'branches': {
             'HEAD': {
                 'target_type': 'alias',
                 'target': 'releases/0.1.0'
             },
             'releases/0.1.0': {
                 'target_type': 'revision',
                 'target': '845673bfe8cbd31b1eaf757745a964137e6f9116',
             },
             'releases/0.1.1-alpha.14': {
                 'target_type': 'revision',
                 'target': '05181c12cd8c22035dd31155656826b85745da37',
             },
         },
     }
     check_snapshot(expected_snapshot, loader.storage)
 
 
 def test_npm_artifact_to_revision_id_none():
     """Current loader version should stop soon if nothing can be found
 
     """
     artifact_metadata = {
         'dist': {
             'shasum': '05181c12cd8c22035dd31155656826b85745da37',
         },
     }
 
     known_artifacts = {
         'b11ebac8c9d0c9e5063a2df693a18e3aba4b2f92': {},
     }
 
     assert artifact_to_revision_id(known_artifacts, artifact_metadata) is None
 
 
 def test_npm_artifact_to_revision_id_old_loader_version():
     """Current loader version should solve old metadata scheme
 
     """
     artifact_metadata = {
         'dist': {
             'shasum': '05181c12cd8c22035dd31155656826b85745da37',
         }
     }
 
     known_artifacts = {
         hash_to_bytes('b11ebac8c9d0c9e5063a2df693a18e3aba4b2f92'): {
             'package_source': {
                 'sha1': "something-wrong"
             }
         },
         hash_to_bytes('845673bfe8cbd31b1eaf757745a964137e6f9116'): {
             'package_source': {
                 'sha1': '05181c12cd8c22035dd31155656826b85745da37',
             }
         }
 
     }
 
     assert artifact_to_revision_id(known_artifacts, artifact_metadata) \
         == hash_to_bytes('845673bfe8cbd31b1eaf757745a964137e6f9116')
 
 
 def test_npm_artifact_to_revision_id_current_loader_version():
     """Current loader version should be able to solve current metadata scheme
 
     """
     artifact_metadata = {
         'dist': {
             'shasum': '05181c12cd8c22035dd31155656826b85745da37',
         }
     }
 
     known_artifacts = {
         hash_to_bytes('b11ebac8c9d0c9e5063a2df693a18e3aba4b2f92'): {
             'original_artifact': [{
                 'checksums': {
                     'sha1': "05181c12cd8c22035dd31155656826b85745da37"
                 },
             }],
         },
         hash_to_bytes('845673bfe8cbd31b1eaf757745a964137e6f9116'): {
             'original_artifact': [{
                 'checksums': {
                     'sha1': 'something-wrong'
                 },
             }],
         },
     }
 
     assert artifact_to_revision_id(known_artifacts, artifact_metadata) \
         == hash_to_bytes('b11ebac8c9d0c9e5063a2df693a18e3aba4b2f92')
 
 
 def test_npm_artifact_with_no_intrinsic_metadata(
         swh_config, requests_mock_datadir):
     """Skip artifact with no intrinsic metadata during ingestion
 
     """
     package = 'nativescript-telerik-analytics'
     url = package_url(package)
     loader = NpmLoader(url)
 
     actual_load_status = loader.load()
     assert actual_load_status['status'] == 'eventful'
 
     # no branch as one artifact without any intrinsic metadata
     expected_snapshot = {
         'id': '1a8893e6a86f444e8be8e7bda6cb34fb1735a00e',
         'branches': {},
     }
     check_snapshot(expected_snapshot, loader.storage)
 
     origin_visit = list(loader.storage.origin_visit_get(url))[-1]
     assert origin_visit['status'] == 'full'
     assert origin_visit['type'] == 'npm'
 
 
 def test_npm_artifact_with_no_upload_time(swh_config, requests_mock_datadir):
     """With no time upload, artifact is skipped
 
     """
     package = 'jammit-no-time'
     url = package_url(package)
     loader = NpmLoader(url)
 
     actual_load_status = loader.load()
     assert actual_load_status['status'] == 'failed'
 
     # no branch as one artifact without any intrinsic metadata
     expected_snapshot = {
         'id': '1a8893e6a86f444e8be8e7bda6cb34fb1735a00e',
         'branches': {},
     }
     check_snapshot(expected_snapshot, loader.storage)
 
     origin_visit = list(loader.storage.origin_visit_get(url))[-1]
     assert origin_visit['status'] == 'partial'
     assert origin_visit['type'] == 'npm'
+
+
+def test_npm_artifact_use_mtime_if_no_time(swh_config, requests_mock_datadir):
+    """With no time upload, artifact is skipped
+
+    """
+    package = 'jammit-express'
+    url = package_url(package)
+    loader = NpmLoader(url)
+
+    actual_load_status = loader.load()
+    assert actual_load_status['status'] == 'eventful'
+
+    # artifact is used
+    expected_snapshot = {
+        'id': 'd6e08e19159f77983242877c373c75222d5ae9dd',
+        'branches': {
+            'HEAD': {
+                'target_type': 'alias',
+                'target': 'releases/0.0.1'
+            },
+            'releases/0.0.1': {
+                'target_type': 'revision',
+                'target': '9e4dd2b40d1b46b70917c0949aa2195c823a648e',
+            }
+        }
+    }
+    check_snapshot(expected_snapshot, loader.storage)
+
+    origin_visit = list(loader.storage.origin_visit_get(url))[-1]
+    assert origin_visit['status'] == 'full'
+    assert origin_visit['type'] == 'npm'