diff --git a/requirements-swh.txt b/requirements-swh.txt
--- a/requirements-swh.txt
+++ b/requirements-swh.txt
@@ -1,7 +1,7 @@
 swh.core >= 0.0.94
 swh.indexer >= 0.0.170
-swh.model >= 0.0.64
+swh.model >= 0.3.0
 swh.scheduler >= 0.0.72
 swh.search >= 0.0.4
 swh.storage >= 0.0.182
 swh.vault >= 0.0.33
\ No newline at end of file
diff --git a/swh/web/api/utils.py b/swh/web/api/utils.py
--- a/swh/web/api/utils.py
+++ b/swh/web/api/utils.py
@@ -228,7 +228,7 @@
                 }
             )
 
-        revision["parents"] = parents
+        revision["parents"] = tuple(parents)
 
     if "children" in revision:
         children = []
diff --git a/swh/web/common/converters.py b/swh/web/common/converters.py
--- a/swh/web/common/converters.py
+++ b/swh/web/common/converters.py
@@ -50,6 +50,8 @@
         return map(lambda y: fmap(f, y), (x for x in data))
     if isinstance(data, list):
         return [fmap(f, x) for x in data]
+    if isinstance(data, tuple):
+        return tuple(fmap(f, x) for x in data)
     if isinstance(data, dict):
         return {k: fmap(f, v) for (k, v) in data.items()}
     return f(data)
diff --git a/swh/web/tests/api/test_utils.py b/swh/web/tests/api/test_utils.py
--- a/swh/web/tests/api/test_utils.py
+++ b/swh/web/tests/api/test_utils.py
@@ -340,7 +340,7 @@
 
     revision_data = archive_data.revision_get(revision)
     del revision_data["directory"]
-    revision_data["parents"].append(parent_revision)
+    revision_data["parents"] = revision_data["parents"] + (parent_revision,)
     revision_data["children"] = child_revision
 
     url = reverse("api-1-revision", url_args={"sha1_git": revision})
@@ -356,7 +356,7 @@
         "api-1-revision-log", url_args={"sha1_git": revision}, request=request
     )
 
-    revision_data["parents"] = [
+    revision_data["parents"] = tuple(
         {
             "id": p["id"],
             "url": reverse(
@@ -364,7 +364,7 @@
             ),
         }
         for p in revision_data["parents"]
-    ]
+    )
 
     revision_data["children_urls"] = [
         reverse(
@@ -399,7 +399,7 @@
         "api-1-revision-log", url_args={"sha1_git": revision}, request=request
     )
 
-    revision_data["parents"] = [
+    revision_data["parents"] = tuple(
         {
             "id": parent_revision,
             "url": reverse(
@@ -408,7 +408,7 @@
                 request=request,
             ),
         }
-    ]
+    )
 
     revision_data["children_urls"] = [
         reverse(
@@ -426,7 +426,7 @@
 
     revision_data = archive_data.revision_get(revision)
     revision_data["message"] = None
-    revision_data["parents"].append(parent_revision)
+    revision_data["parents"] = revision_data["parents"] + (parent_revision,)
     revision_data["children"] = child_revision
 
     url = reverse("api-1-revision", url_args={"sha1_git": revision})
@@ -448,7 +448,7 @@
         "api-1-revision-log", url_args={"sha1_git": revision}, request=request
     )
 
-    revision_data["parents"] = [
+    revision_data["parents"] = tuple(
         {
             "id": p["id"],
             "url": reverse(
@@ -456,7 +456,7 @@
             ),
         }
         for p in revision_data["parents"]
-    ]
+    )
 
     revision_data["children_urls"] = [
         reverse(
@@ -475,7 +475,7 @@
     revision_data = archive_data.revision_get(revision)
     revision_data["message"] = None
     revision_data["message_decoding_failed"] = (True,)
-    revision_data["parents"].append(parent_revision)
+    revision_data["parents"] = revision_data["parents"] + (parent_revision,)
     revision_data["children"] = child_revision
 
     url = reverse("api-1-revision", url_args={"sha1_git": revision})
@@ -501,7 +501,7 @@
         "api-1-revision-log", url_args={"sha1_git": revision}, request=request
     )
 
-    revision_data["parents"] = [
+    revision_data["parents"] = tuple(
         {
             "id": p["id"],
             "url": reverse(
@@ -509,7 +509,7 @@
             ),
         }
         for p in revision_data["parents"]
-    ]
+    )
 
     revision_data["children_urls"] = [
         reverse(
diff --git a/swh/web/tests/common/test_service.py b/swh/web/tests/common/test_service.py
--- a/swh/web/tests/common/test_service.py
+++ b/swh/web/tests/common/test_service.py
@@ -362,14 +362,14 @@
 
     # A directory that points to unknown content
     dir = Directory(
-        entries=[
+        entries=(
             DirectoryEntry(
                 name=bytes(dir_path.encode("utf-8")),
                 type="file",
                 target=hash_to_bytes(unknown_content_["sha1_git"]),
                 perms=DentryPerms.content,
-            )
-        ]
+            ),
+        )
     )
 
     # Create a revision that points to a directory
diff --git a/swh/web/tests/data.py b/swh/web/tests/data.py
--- a/swh/web/tests/data.py
+++ b/swh/web/tests/data.py
@@ -271,7 +271,7 @@
     idx_storage = get_indexer_storage("memory", {})
 
     # Add the empty directory to the test archive
-    storage.directory_add([Directory(entries=[])])
+    storage.directory_add([Directory(entries=())])
 
     # Return tests data
     return {