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
@@ -74,7 +74,7 @@
     kafka_prefix += '.swh.journal.objects'
 
     config = {
-        'brokers': 'localhost:%d' % kafka_server[1],
+        'brokers': ['localhost:%d' % kafka_server[1]],
         'client_id': 'kafka_writer',
         'prefix': kafka_prefix,
     }
@@ -102,7 +102,7 @@
     kafka_prefix += '.swh.journal.objects'
 
     config = {
-        'brokers': 'localhost:%d' % kafka_server[1],
+        'brokers': ['localhost:%d' % kafka_server[1]],
         'client_id': 'kafka_writer',
         'prefix': kafka_prefix,
     }
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
@@ -22,8 +22,11 @@
     def __init__(self, brokers, prefix, client_id):
         self._prefix = prefix
 
+        if isinstance(brokers, str):
+            brokers = [brokers]
+
         self.producer = Producer({
-            'bootstrap.servers': brokers,
+            'bootstrap.servers': ','.join(brokers),
             'client.id': client_id,
             'enable.idempotence': 'true',
         })