diff --git a/test_checker.py b/test_checker.py
index af28e50..6a5ff9c 100644
--- a/test_checker.py
+++ b/test_checker.py
@@ -1,96 +1,110 @@
 # Copyright (C) 2015-2016  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 gzip
 import tempfile
 import unittest
 
 from nose.tools import istest
 from nose.plugins.attrib import attr
 
 from swh.core import hashutil
 from swh.storage.objstorage.objstorage import _obj_path
 from swh.storage.checker.checker import ContentChecker
 
 
 class MockBackupStorage():
 
     def __init__(self):
         self.values = {}
 
     def content_add(self, id, value):
         self.values[id] = value
 
     def content_get(self, ids):
         for id in ids:
             try:
                 data = self.values[id]
             except KeyError:
                 yield None
                 continue
 
             yield {'sha1': id, 'data': data}
 
 
 @attr('fs')
 class TestChecker(unittest.TestCase):
     """ Test the content integrity checker
     """
 
     def setUp(self):
         super().setUp()
         # Connect to an objstorage
         config = {'batch_size': 10}
         path = tempfile.mkdtemp()
         depth = 3
         self.checker = ContentChecker(config, path, depth, 'http://None')
-        self.checker.backup_storage = MockBackupStorage()
+        self.checker.backup_storages = [MockBackupStorage(),
+                                        MockBackupStorage()]
 
     def corrupt_content(self, id):
         """ Make the given content invalid.
         """
         hex_id = hashutil.hash_to_hex(id)
         file_path = _obj_path(hex_id, self.checker.objstorage._root_dir, 3)
         with gzip.open(file_path, 'wb') as f:
             f.write(b'Unexpected content')
 
     @istest
     def check_valid_content(self):
         # Check that a valid content is valid.
         content = b'check_valid_content'
         id = self.checker.objstorage.add_bytes(content)
         self.assertTrue(self.checker.check_content(id))
 
     @istest
     def check_invalid_content(self):
         # Check that an invalid content is noticed.
         content = b'check_invalid_content'
         id = self.checker.objstorage.add_bytes(content)
         self.corrupt_content(id)
         self.assertFalse(self.checker.check_content(id))
 
     @istest
-    def repair_content_present(self):
+    def repair_content_present_first(self):
         # Try to repair a content that is in the backup storage.
-        content = b'repair_content_present'
+        content = b'repair_content_present_first'
+        id = self.checker.objstorage.add_bytes(content)
+        # Add a content to the mock
+        self.checker.backup_storages[0].content_add(id, content)
+        # Corrupt and repair it.
+        self.corrupt_content(id)
+        self.assertFalse(self.checker.check_content(id))
+        self.checker.repair_contents([id])
+        self.assertTrue(self.checker.check_content(id))
+
+    @istest
+    def repair_content_present_second(self):
+        # Try to repair a content that is not in the first backup storage.
+        content = b'repair_content_present_second'
         id = self.checker.objstorage.add_bytes(content)
         # Add a content to the mock
-        self.checker.backup_storage.content_add(id, content)
+        self.checker.backup_storages[1].content_add(id, content)
         # Corrupt and repair it.
         self.corrupt_content(id)
         self.assertFalse(self.checker.check_content(id))
         self.checker.repair_contents([id])
         self.assertTrue(self.checker.check_content(id))
 
     @istest
     def repair_content_missing(self):
         # Try to repair a content that is NOT in the backup storage.
         content = b'repair_content_present'
         id = self.checker.objstorage.add_bytes(content)
         # Corrupt and repair it.
         self.corrupt_content(id)
         self.assertFalse(self.checker.check_content(id))
         self.checker.repair_contents([id])
         self.assertFalse(self.checker.check_content(id))