diff --git a/requirements-swh.txt b/requirements-swh.txt
--- a/requirements-swh.txt
+++ b/requirements-swh.txt
@@ -1,4 +1,4 @@
 swh.core[db,http] >= 2
 swh.counters >= v0.8.0
-swh.model >= 4.4.0
+swh.model >= 6.0.0
 swh.objstorage >= 0.2.2
diff --git a/swh/storage/postgresql/converters.py b/swh/storage/postgresql/converters.py
--- a/swh/storage/postgresql/converters.py
+++ b/swh/storage/postgresql/converters.py
@@ -238,9 +238,9 @@
 
     return Revision(
         id=db_revision["id"],
-        author=author,  # type: ignore  # will pass in swh-model v5.1.0
+        author=author,
         date=date,
-        committer=committer,  # type: ignore  # will pass in swh-model v5.1.0
+        committer=committer,
         committer_date=committer_date,
         type=RevisionType(db_revision["type"]),
         directory=db_revision["directory"],
diff --git a/swh/storage/proxies/buffer.py b/swh/storage/proxies/buffer.py
--- a/swh/storage/proxies/buffer.py
+++ b/swh/storage/proxies/buffer.py
@@ -65,8 +65,10 @@
     if revision.message:
         s += len(revision.message)
 
-    s += len(revision.author.fullname)
-    s += len(revision.committer.fullname)
+    if revision.author is not None:
+        s += len(revision.author.fullname)
+    if revision.committer is not None:
+        s += len(revision.committer.fullname)
     s += sum(len(h) + len(v) for h, v in revision.extra_headers)
 
     return s
diff --git a/swh/storage/tests/storage_tests.py b/swh/storage/tests/storage_tests.py
--- a/swh/storage/tests/storage_tests.py
+++ b/swh/storage/tests/storage_tests.py
@@ -4,7 +4,6 @@
 # See top-level LICENSE file for more information
 
 from collections import defaultdict
-import contextlib
 import datetime
 from datetime import timedelta
 import inspect
@@ -56,16 +55,6 @@
 )
 
 
-@contextlib.contextmanager
-def disable_attrs_validator():
-    v = attr.validators.get_disabled()
-    try:
-        attr.validators.set_disabled(True)
-        yield
-    finally:
-        attr.validators.set_disabled(v)
-
-
 def transform_entries(
     storage: StorageInterface, dir_: Directory, *, prefix: bytes = b""
 ) -> Iterator[Dict[str, Any]]:
@@ -1161,8 +1150,12 @@
                 revision,
                 synthetic=False,
                 metadata=None,
-                committer=Person.from_fullname(revision.committer.fullname),
-                author=Person.from_fullname(revision.author.fullname),
+                author=None
+                if revision.author is None
+                else Person.from_fullname(revision.author.fullname),
+                committer=None
+                if revision.committer is None
+                else Person.from_fullname(revision.committer.fullname),
                 type=RevisionType.GIT,
             )
             for revision in revisions
@@ -1322,12 +1315,9 @@
     def test_revision_add_no_author_or_date(self, swh_storage, sample_data):
         full_revision = sample_data.revision
 
-        with disable_attrs_validator():
-            # TODO: remove context manager when support for author=None
-            # lands in swh-model
-            revision = attr.evolve(full_revision, author=None, date=None)
-            revision = attr.evolve(revision, id=revision.compute_hash())
-            actual_result = swh_storage.revision_add([revision])
+        revision = attr.evolve(full_revision, author=None, date=None)
+        revision = attr.evolve(revision, id=revision.compute_hash())
+        actual_result = swh_storage.revision_add([revision])
         assert actual_result == {"revision:add": 1}
 
         end_missing = swh_storage.revision_missing([revision.id])
@@ -1337,20 +1327,14 @@
             ("revision", revision)
         ]
 
-        with disable_attrs_validator():
-            # TODO: remove context manager when support for author=None
-            # lands in swh-model
-            assert swh_storage.revision_get([revision.id]) == [revision]
+        assert swh_storage.revision_get([revision.id]) == [revision]
 
     def test_revision_add_no_committer_or_date(self, swh_storage, sample_data):
         full_revision = sample_data.revision
 
-        with disable_attrs_validator():
-            # TODO: remove context manager when support for author=None
-            # lands in swh-model
-            revision = attr.evolve(full_revision, committer=None, committer_date=None)
-            revision = attr.evolve(revision, id=revision.compute_hash())
-            actual_result = swh_storage.revision_add([revision])
+        revision = attr.evolve(full_revision, committer=None, committer_date=None)
+        revision = attr.evolve(revision, id=revision.compute_hash())
+        actual_result = swh_storage.revision_add([revision])
         assert actual_result == {"revision:add": 1}
 
         end_missing = swh_storage.revision_missing([revision.id])
@@ -1360,10 +1344,7 @@
             ("revision", revision)
         ]
 
-        with disable_attrs_validator():
-            # TODO: remove context manager when support for author=None
-            # lands in swh-model
-            assert swh_storage.revision_get([revision.id]) == [revision]
+        assert swh_storage.revision_get([revision.id]) == [revision]
 
     def test_extid_add_git(self, swh_storage, sample_data):