diff --git a/swh/deposit/api/private/deposit_read.py b/swh/deposit/api/private/deposit_read.py
--- a/swh/deposit/api/private/deposit_read.py
+++ b/swh/deposit/api/private/deposit_read.py
@@ -95,7 +95,7 @@
         with aggregate_tarballs(self.extraction_dir, archive_paths) as path:
             return FileResponse(open(path, 'rb'),
                                 status=status.HTTP_200_OK,
-                                content_type='application/octet-stream')
+                                content_type='application/zip')
 
 
 class SWHDepositReadMetadata(SWHPrivateAPIView, SWHGetDepositAPI,
diff --git a/swh/deposit/tests/api/test_deposit_private_read_archive.py b/swh/deposit/tests/api/test_deposit_private_read_archive.py
--- a/swh/deposit/tests/api/test_deposit_private_read_archive.py
+++ b/swh/deposit/tests/api/test_deposit_private_read_archive.py
@@ -36,7 +36,7 @@
         r = authenticated_client.get(url)
 
         assert r.status_code == status.HTTP_200_OK
-        assert r._headers['content-type'][1] == 'application/octet-stream'
+        assert r._headers['content-type'][1] == 'application/zip'
 
         # read the stream
         data = b''.join(r.streaming_content)
@@ -76,7 +76,7 @@
         r = authenticated_client.get(url)
 
         assert r.status_code == status.HTTP_200_OK
-        assert r._headers['content-type'][1] == 'application/octet-stream'
+        assert r._headers['content-type'][1] == 'application/zip'
         # read the stream
         data = b''.join(r.streaming_content)
         # extract the file from the zip