diff --git a/requirements-swh.txt b/requirements-swh.txt
--- a/requirements-swh.txt
+++ b/requirements-swh.txt
@@ -1,2 +1,2 @@
 swh.core[db,http] >= 0.0.60
-swh.model >= 0.2
+swh.model >= 0.3
diff --git a/swh/journal/tests/journal_data.py b/swh/journal/tests/journal_data.py
--- a/swh/journal/tests/journal_data.py
+++ b/swh/journal/tests/journal_data.py
@@ -89,7 +89,7 @@
         "directory": b"\x01" * 20,
         "synthetic": False,
         "metadata": None,
-        "parents": [],
+        "parents": (),
     },
     {
         "id": hash_to_bytes("368a48fe15b7db2383775f97c6b247011b3f14f4"),
@@ -102,7 +102,7 @@
         "directory": b"\x02" * 20,
         "synthetic": False,
         "metadata": None,
-        "parents": [],
+        "parents": (),
     },
 ]
 
diff --git a/swh/journal/tests/test_client.py b/swh/journal/tests/test_client.py
--- a/swh/journal/tests/test_client.py
+++ b/swh/journal/tests/test_client.py
@@ -35,7 +35,7 @@
     ),
     "synthetic": False,
     "metadata": None,
-    "parents": [],
+    "parents": (),
     "id": b"\x8b\xeb\xd1\x9d\x07\xe2\x1e0\xe2 \x91X\x8d\xbd\x1c\xa8\x86\xdeB\x0c",
 }
 
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
@@ -121,7 +121,7 @@
         brokers=[kafka_server], client_id="kafka_writer", prefix=kafka_prefix,
     )
 
-    empty_dir = Directory(entries=[])
+    empty_dir = Directory(entries=())
     with pytest.raises(KafkaDeliveryError) as exc:
         writer.write_addition("directory", empty_dir)
 
@@ -153,7 +153,7 @@
         producer_class=MockProducer,
     )
 
-    empty_dir = Directory(entries=[])
+    empty_dir = Directory(entries=())
     with pytest.raises(KafkaDeliveryError) as exc:
         writer.write_addition("directory", empty_dir)