diff --git a/swh/core/api/asynchronous.py b/swh/core/api/asynchronous.py
index 7574f36..bd3f453 100644
--- a/swh/core/api/asynchronous.py
+++ b/swh/core/api/asynchronous.py
@@ -1,60 +1,60 @@
 import json
 import logging
 import pickle
 import sys
 import traceback
 
 import aiohttp.web
 from deprecated import deprecated
 import multidict
 
 from .serializers import msgpack_dumps, msgpack_loads, SWHJSONDecoder
 
 
 def encode_data_server(data, **kwargs):
     return aiohttp.web.Response(
         body=msgpack_dumps(data),
         headers=multidict.MultiDict({'Content-Type': 'application/x-msgpack'}),
         **kwargs
     )
 
 
 async def decode_request(request):
     content_type = request.headers.get('Content-Type')
     data = await request.read()
     if not data:
         return {}
     if content_type == 'application/x-msgpack':
         r = msgpack_loads(data)
     elif content_type == 'application/json':
-        r = json.loads(data, cls=SWHJSONDecoder)
+        r = json.loads(data.decode(), cls=SWHJSONDecoder)
     else:
         raise ValueError('Wrong content type `%s` for API request'
                          % content_type)
     return r
 
 
 async def error_middleware(app, handler):
     async def middleware_handler(request):
         try:
             return (await handler(request))
         except Exception as e:
             if isinstance(e, aiohttp.web.HTTPException):
                 raise
             logging.exception(e)
             exception = traceback.format_exception(*sys.exc_info())
             res = {'exception': exception,
                    'exception_pickled': pickle.dumps(e)}
             return encode_data_server(res, status=500)
     return middleware_handler
 
 
 class RPCServerApp(aiohttp.web.Application):
     def __init__(self, *args, middlewares=(), **kwargs):
         middlewares = (error_middleware,) + middlewares
         super().__init__(*args, middlewares=middlewares, **kwargs)
 
 
 SWHRemoteAPI = deprecated(
     version='0.0.64',
     reason='Use the RPCServerApp instead')(RPCServerApp)