diff --git a/swh/journal/tests/test_kafka_writer.py b/swh/journal/tests/test_kafka_writer.py
--- a/swh/journal/tests/test_kafka_writer.py
+++ b/swh/journal/tests/test_kafka_writer.py
@@ -77,6 +77,9 @@
         'brokers': ['localhost:%d' % kafka_server[1]],
         'client_id': 'kafka_writer',
         'prefix': kafka_prefix,
+        'producer_config': {
+            'message.max.bytes': 100000000,
+        }
     }
 
     writer = KafkaJournalWriter(**config)
@@ -105,10 +108,13 @@
         'brokers': ['localhost:%d' % kafka_server[1]],
         'client_id': 'kafka_writer',
         'prefix': kafka_prefix,
+        'producer_config': {
+            'message.max.bytes': 100000000,
+        }
     }
 
     storage = get_storage('memory', journal_writer={
-        'cls': 'kafka', 'args': config,
+        'cls': 'kafka', **config,
     })
 
     expected_messages = 0
diff --git a/swh/journal/writer/kafka.py b/swh/journal/writer/kafka.py
--- a/swh/journal/writer/kafka.py
+++ b/swh/journal/writer/kafka.py
@@ -19,12 +19,15 @@
     """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):
+    def __init__(self, brokers, prefix, client_id, producer_config=None):
         self._prefix = prefix
 
         if isinstance(brokers, str):
             brokers = [brokers]
 
+        if not producer_config:
+            producer_config = {}
+
         self.producer = Producer({
             'bootstrap.servers': ','.join(brokers),
             'client.id': client_id,
@@ -32,6 +35,7 @@
             'error_cb': self._error_cb,
             'logger': logger,
             'enable.idempotence': 'true',
+            **producer_config,
         })
 
     def _error_cb(self, error):