diff --git a/swh/journal/direct_writer.py b/swh/journal/direct_writer.py
index 28e6ead..17a5dc1 100644
--- a/swh/journal/direct_writer.py
+++ b/swh/journal/direct_writer.py
@@ -1,75 +1,78 @@
 # 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 logging
 
 from kafka import KafkaProducer
 
 from swh.model.hashutil import DEFAULT_ALGORITHMS
+from swh.model.model import BaseModel
 
 from .serializers import key_to_kafka, value_to_kafka
 
 logger = logging.getLogger(__name__)
 
 
 class DirectKafkaWriter:
     """This class is instantiated and used by swh-storage to write incoming
     new objects to Kafka before adding them to the storage backend
     (eg. postgresql) itself."""
     def __init__(self, brokers, prefix, client_id):
         self._prefix = prefix
 
         self.producer = KafkaProducer(
             bootstrap_servers=brokers,
             key_serializer=key_to_kafka,
             value_serializer=value_to_kafka,
             client_id=client_id,
         )
 
     def send(self, topic, key, value):
         self.producer.send(topic=topic, key=key, value=value)
 
     def _get_key(self, object_type, object_):
         if object_type in ('revision', 'release', 'directory', 'snapshot'):
             return object_['id']
         elif object_type == 'content':
             return object_['sha1']  # TODO: use a dict of hashes
         elif object_type == 'skipped_content':
             return {
                 hash: object_[hash]
                 for hash in DEFAULT_ALGORITHMS
             }
         elif object_type == 'origin':
             return {'url': object_['url'], 'type': object_['type']}
         elif object_type == 'origin_visit':
             return {
                 'origin': object_['origin'],
                 'date': str(object_['date']),
             }
         else:
             raise ValueError('Unknown object type: %s.' % object_type)
 
     def _sanitize_object(self, object_type, object_):
         if object_type == 'origin_visit':
             return {
                 **object_,
                 'date': str(object_['date']),
             }
         elif object_type == 'origin':
             assert 'id' not in object_
         return object_
 
     def write_addition(self, object_type, object_):
+        if isinstance(object_, BaseModel):
+            object_ = object_.to_dict()
         topic = '%s.%s' % (self._prefix, object_type)
         key = self._get_key(object_type, object_)
         object_ = self._sanitize_object(object_type, object_)
         logger.debug('topic: %s, key: %s, value: %s', topic, key, object_)
         self.send(topic, key=key, value=object_)
 
     write_update = write_addition
 
     def write_additions(self, object_type, objects):
         for object_ in objects:
             self.write_addition(object_type, object_)