diff --git a/sonar/modules/documents/marshmallow/json.py b/sonar/modules/documents/marshmallow/json.py
index 0313ce4e..f7001de1 100644
--- a/sonar/modules/documents/marshmallow/json.py
+++ b/sonar/modules/documents/marshmallow/json.py
@@ -47,9 +47,18 @@ class ThumbnailSchemaV1(StrictKeysMixin):
 
     class Meta:
         """Meta for file schema."""
+        unknown = EXCLUDE
+
+    key = SanitizedUnicode()
+    label = SanitizedUnicode()
+    type = SanitizedUnicode()
+    order = fields.Integer()
+    restriction = fields.Dict(dump_only=True)
+    links = fields.Dict(dump_only=True)
     thumbnail = SanitizedUnicode(dump_only=True)
 
 
+
 class FileSchemaV1(ThumbnailSchemaV1):
     """File schema."""
 
@@ -64,20 +73,13 @@ class Meta:
     bucket = SanitizedUnicode()
     file_id = SanitizedUnicode()
     version_id = SanitizedUnicode()
-    key = SanitizedUnicode()
     mimetype = SanitizedUnicode()
     checksum = SanitizedUnicode()
     size = fields.Integer()
-    label = SanitizedUnicode()
-    type = SanitizedUnicode()
-    order = fields.Integer()
     external_url = SanitizedUnicode()
     access = SanitizedUnicode()
     restricted_outside_organisation = fields.Boolean()
     embargo_date = SanitizedUnicode()
-    restriction = fields.Dict(dump_only=True)
-    links = fields.Dict(dump_only=True)
-    thumbnail = SanitizedUnicode(dump_only=True)
     permissions = fields.Dict(dump_only=True)
 
     @pre_dump
diff --git a/tests/api/documents/test_documents_rest.py b/tests/api/documents/test_documents_rest.py
index d690663a..af673233 100644
--- a/tests/api/documents/test_documents_rest.py
+++ b/tests/api/documents/test_documents_rest.py
@@ -29,7 +29,11 @@ def test_get(client, document_with_file):
     assert res.status_code == 200
     assert res.json['hits']['total']['value'] == 1
     # the search results does not contains permissions
-    assert not res.json['hits']['hits'][0]['metadata']['_files'][0].get("permissions")
+    fdata = res.json['hits']['hits'][0]['metadata']['_files'][0]
+    assert list(fdata.keys()) == [
+        'key', 'label', 'type', 'order', 'restriction', 'links', 'thumbnail'
+    ]
+    assert not fdata.get("permissions")
 
     # the item result should contains permissions
     res = client.get(url_for('invenio_records_rest.doc_item', pid_value=document_with_file['pid']))