diff --git a/requirements.txt b/requirements.txt
--- a/requirements.txt
+++ b/requirements.txt
@@ -5,7 +5,7 @@
 flask
 iso8601
 mypy_extensions
-psycopg2
+psycopg2 >= 2.9.0  # v2.9.0 fixes truncation of non-integer timezones
 redis
 tenacity >= 6.2
 typing-extensions
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
@@ -37,6 +37,8 @@
     Snapshot,
     SnapshotBranch,
     TargetType,
+    Timestamp,
+    TimestampWithTimezone,
 )
 from swh.model.swhids import CoreSWHID, ObjectType
 from swh.storage import get_storage
@@ -1017,6 +1019,35 @@
             ("revision", revision2),
         ]
 
+    def test_revision_add_fractional_timezone(self, swh_storage, sample_data):
+        # When reading a date from this time period, postgresql returns them
+        # with UTC+00:09:21 as timezone, but psycopg2 < 2.9.0 had to truncate them.
+        # https://www.psycopg.org/docs/usage.html#time-zones-handling
+        #
+        # Therefore, this test fails with psycopg2 < 2.9.0.
+        revision = attr.evolve(
+            sample_data.revision,
+            date=TimestampWithTimezone(
+                timestamp=Timestamp(seconds=-1855958962, microseconds=0),
+                offset=0,
+                negative_utc=False,
+            ),
+        )
+        init_missing = swh_storage.revision_missing([revision.id])
+        assert list(init_missing) == [revision.id]
+
+        actual_result = swh_storage.revision_add([revision])
+        assert actual_result == {"revision:add": 1}
+
+        end_missing = swh_storage.revision_missing([revision.id])
+        assert list(end_missing) == []
+
+        assert list(swh_storage.journal_writer.journal.objects) == [
+            ("revision", revision)
+        ]
+
+        assert swh_storage.revision_get([revision.id])[0] == revision
+
     def test_revision_add_name_clash(self, swh_storage, sample_data):
         revision, revision2 = sample_data.revisions[:2]