diff --git a/swh/storage/cassandra/converters.py b/swh/storage/cassandra/converters.py
index 253ba3cd..a25b3163 100644
--- a/swh/storage/cassandra/converters.py
+++ b/swh/storage/cassandra/converters.py
@@ -1,96 +1,96 @@
 # Copyright (C) 2019-2020  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
 
 import datetime
 import json
 import attr
 
 from copy import deepcopy
 from typing import Any, Dict, Tuple
 
 from cassandra.cluster import ResultSet
 
 from swh.model.model import (
     ObjectType,
     OriginVisitStatus,
     Revision,
     RevisionType,
     Release,
     Sha1Git,
 )
 from swh.model.hashutil import DEFAULT_ALGORITHMS
 
 from .common import Row
 
 
 def revision_to_db(revision: Revision) -> Dict[str, Any]:
     # we use a deepcopy of the dict because we do not want to recurse the
     # Model->dict conversion (to keep Timestamp & al. entities), BUT we do not
     # want to modify original metadata (embedded in the Model entity), so we
     # non-recursively convert it as a dict but make a deep copy.
     db_revision = deepcopy(attr.asdict(revision, recurse=False))
     metadata = revision.metadata
     extra_headers = revision.extra_headers
     if not extra_headers and metadata and "extra_headers" in metadata:
         extra_headers = db_revision["metadata"].pop("extra_headers")
     db_revision["metadata"] = json.dumps(
-        dict(db_revision["metadata"] if db_revision["metadata"] is not None else None)
+        dict(db_revision["metadata"]) if db_revision["metadata"] is not None else None
     )
     db_revision["extra_headers"] = extra_headers
     db_revision["type"] = db_revision["type"].value
     return db_revision
 
 
 def revision_from_db(db_revision: Row, parents: Tuple[Sha1Git]) -> Revision:
     revision = db_revision._asdict()  # type: ignore
     metadata = json.loads(revision.pop("metadata", None))
     extra_headers = revision.pop("extra_headers", ())
     if not extra_headers and metadata and "extra_headers" in metadata:
         extra_headers = metadata.pop("extra_headers")
     if extra_headers is None:
         extra_headers = ()
     return Revision(
         parents=parents,
         type=RevisionType(revision.pop("type")),
         metadata=metadata,
         extra_headers=extra_headers,
         **revision,
     )
 
 
 def release_to_db(release: Release) -> Dict[str, Any]:
     db_release = attr.asdict(release, recurse=False)
     db_release["target_type"] = db_release["target_type"].value
     return db_release
 
 
 def release_from_db(db_release: Row) -> Release:
     release = db_release._asdict()  # type: ignore
     return Release(target_type=ObjectType(release.pop("target_type")), **release,)
 
 
 def row_to_content_hashes(row: Row) -> Dict[str, bytes]:
     """Convert cassandra row to a content hashes
 
     """
     hashes = {}
     for algo in DEFAULT_ALGORITHMS:
         hashes[algo] = getattr(row, algo)
     return hashes
 
 
 def row_to_visit_status(row: ResultSet) -> OriginVisitStatus:
     """Format a row representing a visit_status to an actual dict representing an
     OriginVisitStatus.
 
     """
     return OriginVisitStatus.from_dict(
         {
             **row._asdict(),
             "origin": row.origin,
             "date": row.date.replace(tzinfo=datetime.timezone.utc),
             "metadata": (json.loads(row.metadata) if row.metadata else None),
         }
     )