diff --git a/swh/objstorage/objstorage_rados.py b/swh/objstorage/objstorage_rados.py
index 82e41ca..9390287 100644
--- a/swh/objstorage/objstorage_rados.py
+++ b/swh/objstorage/objstorage_rados.py
@@ -1,87 +1,91 @@
 # Copyright (C) 2018  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
 import rados
 
 from swh.model import hashutil
 
 from swh.objstorage.exc import ObjNotFoundError
 from swh.objstorage import objstorage
 
 READ_SIZE = 8192
 
 
 class RADOSObjStorage(objstorage.ObjStorage):
     """Object storage implemented with RADOS"""
 
     def __init__(self, *, rados_id, pool_name, ceph_config,
                  allow_delete=False):
         super().__init__(allow_delete=allow_delete)
         self.pool_name = pool_name
-        self.cluster = rados.Rados(rados_id=rados_id, conf=ceph_config)
+        self.cluster = rados.Rados(
+            conf=ceph_config,
+            conffile='',
+            rados_id=rados_id,
+        )
         self.cluster.connect()
         self.__ioctx = None
 
     def check_config(self, *, check_write):
         if self.pool_name not in self.cluster.list_pools():
             raise ValueError('Pool %s does not exist' % self.pool_name)
 
     @staticmethod
     def _to_rados_obj_id(obj_id):
         """Convert to a RADOS object identifier"""
         return hashutil.hash_to_hex(obj_id)
 
     @property
     def ioctx(self):
         if not self.__ioctx:
             self.__ioctx = self.cluster.open_ioctx(self.pool_name)
         return self.__ioctx
 
     def __contains__(self, obj_id):
         try:
             self.ioctx.stat(self._to_rados_obj_id(obj_id))
         except rados.ObjectNotFound:
             return False
         else:
             return True
 
     def add(self, content, obj_id=None, check_presence=True):
         if not obj_id:
             raise ValueError('add needs an obj_id')
 
         _obj_id = self._to_rados_obj_id(obj_id)
 
         if check_presence:
             try:
                 self.ioctx.stat(_obj_id)
             except rados.ObjectNotFound:
                 pass
             else:
                 return obj_id
         self.ioctx.write_full(_obj_id, content)
 
         return obj_id
 
     def get(self, obj_id):
         chunks = []
         _obj_id = self._to_rados_obj_id(obj_id)
         try:
             length, mtime = self.ioctx.stat(_obj_id)
         except rados.ObjectNotFound:
             raise ObjNotFoundError(obj_id) from None
         offset = 0
         while offset < length:
             chunk = self.ioctx.read(_obj_id, offset, READ_SIZE)
             chunks.append(chunk)
             offset += len(chunk)
 
         return b''.join(chunks)
 
     def check(self, obj_id):
         return True
 
     def delete(self, obj_id):
         super().delete(obj_id)  # check delete permission
         return True