diff --git a/src/calibre/srv/http_response.py b/src/calibre/srv/http_response.py
index b5b16fbe8f..8313d18e32 100644
--- a/src/calibre/srv/http_response.py
+++ b/src/calibre/srv/http_response.py
@@ -29,7 +29,7 @@ from calibre.utils.monotonic import monotonic
 from polyglot import http_client, reprlib
 
 Range = namedtuple('Range', 'start stop size')
-MULTIPART_SEPARATOR = uuid.uuid4().hex.decode('ascii')
+MULTIPART_SEPARATOR = uuid.uuid4().hex
 COMPRESSIBLE_TYPES = {'application/json', 'application/javascript', 'application/xml', 'application/oebps-package+xml'}
 if is_py3:
     import zlib