diff --git a/swh/journal/tests/conftest.py b/swh/journal/tests/conftest.py
--- a/swh/journal/tests/conftest.py
+++ b/swh/journal/tests/conftest.py
@@ -6,6 +6,8 @@
 import os
 import pytest
 import logging
+import random
+import string
 
 from kafka import KafkaProducer, KafkaConsumer
 from subprocess import Popen
@@ -177,16 +179,21 @@
 
 
 # Those defines fixtures
-zookeeper_proc = make_zookeeper_process(ZOOKEEPER_BIN)
+zookeeper_proc = make_zookeeper_process(ZOOKEEPER_BIN, scope='session')
 os.environ['KAFKA_LOG4J_OPTS'] = \
     '-Dlog4j.configuration=file:%s/log4j.properties' % \
     os.path.dirname(__file__)
-kafka_server = make_kafka_server(KAFKA_BIN, 'zookeeper_proc')
+kafka_server = make_kafka_server(KAFKA_BIN, 'zookeeper_proc', scope='session')
 
 logger = logging.getLogger('kafka')
 logger.setLevel(logging.WARN)
 
 
+@pytest.fixture(scope='function')
+def kafka_prefix():
+    return ''.join(random.choice(string.ascii_lowercase) for _ in range(10))
+
+
 @pytest.fixture
 def test_config():
     """Test configuration needed for publisher/producer/consumer
@@ -215,12 +222,14 @@
 
 @pytest.fixture
 def consumer_from_publisher(kafka_server: Tuple[Popen, int],
+                            kafka_prefix: str,
                             test_config: Dict) -> KafkaConsumer:
     """Get a connected Kafka consumer.
 
     """
-    kafka_topics = ['%s.%s' % (test_config['final_prefix'], object_type)
-                    for object_type in test_config['object_types']]
+    kafka_topics = [
+        '%s.%s.%s' % (kafka_prefix, test_config['final_prefix'], object_type)
+        for object_type in test_config['object_types']]
     _, kafka_port = kafka_server
     consumer = KafkaConsumer(
         *kafka_topics,
diff --git a/swh/journal/tests/test_direct_writer.py b/swh/journal/tests/test_direct_writer.py
--- a/swh/journal/tests/test_direct_writer.py
+++ b/swh/journal/tests/test_direct_writer.py
@@ -18,7 +18,7 @@
 from .conftest import OBJECT_TYPE_KEYS
 
 
-def assert_written(consumer):
+def assert_written(consumer, kafka_prefix):
     time.sleep(0.1)  # Without this, some messages are missing
 
     consumed_objects = defaultdict(list)
@@ -26,7 +26,7 @@
         consumed_objects[msg.topic].append((msg.key, msg.value))
 
     for (object_type, (key_name, objects)) in OBJECT_TYPE_KEYS.items():
-        topic = 'swh.journal.objects.%s' % object_type
+        topic = kafka_prefix + '.' + object_type
         (keys, values) = zip(*consumed_objects[topic])
         if key_name:
             assert list(keys) == [object_[key_name] for object_ in objects]
@@ -42,13 +42,15 @@
 
 
 def test_direct_writer(
+        kafka_prefix: str,
         kafka_server: Tuple[Popen, int],
         consumer_from_publisher: KafkaConsumer):
+    kafka_prefix += '.swh.journal.objects'
 
     config = {
         'brokers': 'localhost:%d' % kafka_server[1],
         'client_id': 'direct_writer',
-        'prefix': 'swh.journal.objects',
+        'prefix': kafka_prefix,
     }
 
     writer = DirectKafkaWriter(**config)
@@ -59,17 +61,19 @@
                 object_ = {**object_, 'visit': num}
             writer.write_addition(object_type, object_)
 
-    assert_written(consumer_from_publisher)
+    assert_written(consumer_from_publisher, kafka_prefix)
 
 
 def test_storage_direct_writer(
+        kafka_prefix: str,
         kafka_server: Tuple[Popen, int],
         consumer_from_publisher: KafkaConsumer):
+    kafka_prefix += '.swh.journal.objects'
 
     config = {
         'brokers': 'localhost:%d' % kafka_server[1],
         'client_id': 'direct_writer',
-        'prefix': 'swh.journal.objects',
+        'prefix': kafka_prefix,
     }
 
     storage = get_storage('memory', {'journal_writer': {
@@ -92,4 +96,4 @@
         else:
             assert False, object_type
 
-    assert_written(consumer_from_publisher)
+    assert_written(consumer_from_publisher, kafka_prefix)
diff --git a/swh/journal/tests/test_replay.py b/swh/journal/tests/test_replay.py
--- a/swh/journal/tests/test_replay.py
+++ b/swh/journal/tests/test_replay.py
@@ -19,8 +19,10 @@
 
 
 def test_storage_play(
+        kafka_prefix: str,
         kafka_server: Tuple[Popen, int]):
     (_, port) = kafka_server
+    kafka_prefix += '.swh.journal.objects'
 
     storage = get_storage('memory', {})
 
@@ -34,7 +36,7 @@
     # Fill Kafka
     nb_sent = 0
     for (object_type, (_, objects)) in OBJECT_TYPE_KEYS.items():
-        topic = 'swh.journal.objects.' + object_type
+        topic = kafka_prefix + '.' + object_type
         for object_ in objects:
             key = bytes(random.randint(0, 255) for _ in range(40))
             producer.send(topic, key=key, value=object_)
@@ -44,7 +46,7 @@
     config = {
         'brokers': 'localhost:%d' % kafka_server[1],
         'consumer_id': 'replayer',
-        'prefix': 'swh.journal.objects',
+        'prefix': kafka_prefix,
     }
     replayer = StorageReplayer(**config)
     nb_inserted = replayer.fill(storage, max_messages=nb_sent)