diff --git a/requirements-swh.txt b/requirements-swh.txt
index 2abb671..33a001b 100644
--- a/requirements-swh.txt
+++ b/requirements-swh.txt
@@ -1,4 +1,4 @@
 swh.storage >= 0.11.3
-swh.model >= 0.4.0
+swh.model >= 4.3.0
 swh.scheduler >= 0.0.39
 swh.loader.core >= 0.18
diff --git a/swh/loader/svn/tests/test_converters.py b/swh/loader/svn/tests/test_converters.py
index 58c7238..2021918 100644
--- a/swh/loader/svn/tests/test_converters.py
+++ b/swh/loader/svn/tests/test_converters.py
@@ -1,124 +1,120 @@
 # Copyright (C) 2015-2020  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 swh.loader.svn import converters
 from swh.model.hashutil import hash_to_bytes
 from swh.model.model import Person, Revision, Timestamp, TimestampWithTimezone
 
 
 def test_svn_author_to_swh_person():
     """The author should have name, email and fullname filled.
 
     """
     actual_person = converters.svn_author_to_swh_person(b"tony <ynot@dagobah>")
 
     assert actual_person == Person.from_dict(
         {"fullname": b"tony <ynot@dagobah>", "name": b"tony", "email": b"ynot@dagobah",}
     )
 
 
 def test_svn_author_to_swh_person_no_email():
     """The author and fullname should be the same as the input (author).
 
     """
     actual_person = converters.svn_author_to_swh_person(b"tony")
     assert actual_person == Person.from_dict(
         {"fullname": b"tony", "name": b"tony", "email": None,}
     )
 
 
 def test_svn_author_to_swh_person_empty_person():
     """Empty person has only its fullname filled with the empty
     byte-string.
 
     """
     actual_person = converters.svn_author_to_swh_person(b"")
     assert actual_person == Person.from_dict(
         {"fullname": b"", "name": None, "email": None,}
     )
 
 
 def test_build_swh_revision_default():
     """This should build the swh revision with the swh revision's extra
     headers about the repository.
 
     """
     dir_id = hash_to_bytes("d6e08e19159f77983242877c373c75222d5ae9dd")
     date = TimestampWithTimezone(
-        timestamp=Timestamp(seconds=1088108379, microseconds=0),
-        offset=0,
-        negative_utc=False,
+        timestamp=Timestamp(seconds=1088108379, microseconds=0), offset_bytes=b"+0000"
     )
     actual_rev = converters.build_swh_revision(
         repo_uuid=b"uuid",
         dir_id=dir_id,
         commit={
             "author_name": Person(
                 name=b"theo", email=b"theo@uuid", fullname=b"theo <theo@uuid>"
             ),
             "message": b"commit message",
             "author_date": date,
         },
         rev=10,
         parents=(),
     )
 
     expected_rev = Revision.from_dict(
         {
             "date": date.to_dict(),
             "committer_date": date.to_dict(),
             "type": "svn",
             "directory": dir_id,
             "message": b"commit message",
             "author": {
                 "name": b"theo",
                 "email": b"theo@uuid",
                 "fullname": b"theo <theo@uuid>",
             },
             "committer": {
                 "name": b"theo",
                 "email": b"theo@uuid",
                 "fullname": b"theo <theo@uuid>",
             },
             "synthetic": True,
             "extra_headers": ((b"svn_repo_uuid", b"uuid"), (b"svn_revision", b"10"),),
             "parents": (),
         }
     )
 
     assert actual_rev == expected_rev
 
 
 def test_svn_date_to_swh_date():
     """The timestamp should not be tampered with and include the
     decimals.
 
     """
     assert converters.svn_date_to_swh_date(
         b"2011-05-31T06:04:39.500900Z"
     ) == TimestampWithTimezone(
         timestamp=Timestamp(seconds=1306821879, microseconds=500900),
-        offset=0,
-        negative_utc=False,
+        offset_bytes=b"+0000",
     )
 
     assert converters.svn_date_to_swh_date(
         b"2011-05-31T06:04:39.800722Z"
     ) == TimestampWithTimezone(
         timestamp=Timestamp(seconds=1306821879, microseconds=800722),
-        offset=0,
-        negative_utc=False,
+        offset_bytes=b"+0000",
     )
 
 
 def test_svn_date_to_swh_date_epoch():
     """Empty date should be EPOCH (timestamp and offset at 0)."""
     # It should return 0, epoch
     default_tstz = TimestampWithTimezone(
-        timestamp=Timestamp(seconds=0, microseconds=0), offset=0, negative_utc=False,
+        timestamp=Timestamp(seconds=0, microseconds=0), offset_bytes=b"+0000"
     )
 
     assert converters.svn_date_to_swh_date("") == default_tstz
     assert converters.svn_date_to_swh_date(None) == default_tstz