diff --git a/util/registry/torrent.py b/util/registry/torrent.py
index 400b00836..fe6ea49f0 100644
--- a/util/registry/torrent.py
+++ b/util/registry/torrent.py
@@ -58,7 +58,7 @@ def public_torrent_filename(blob_uuid):
   return hashlib.sha256(blob_uuid).hexdigest()
 
 def per_user_torrent_filename(user_uuid, blob_uuid):
-  return hashlib.sha256(blob_uuid + user_uuid + FILENAME_PEPPER).hexdigest()
+  return hashlib.sha256(FILENAME_PEPPER + "||" + blob_uuid + "||" + user_uuid).hexdigest()
 
 
 class PieceHasher(object):