diff --git a/zaqar/storage/mongodb/options.py b/zaqar/storage/mongodb/options.py
index 627d9b52d..74667601b 100644
--- a/zaqar/storage/mongodb/options.py
+++ b/zaqar/storage/mongodb/options.py
@@ -75,7 +75,7 @@ _COMMON_OPTIONS = (
                                 group=_deprecated_group), ],
                help='Database name.'),
 
-    cfg.IntOpt('max_attempts', default=1000,
+    cfg.IntOpt('max_attempts', min=0, default=1000,
                deprecated_opts=[cfg.DeprecatedOpt(
                                 'max_attempts',
                                 group=_deprecated_group), ],
diff --git a/zaqar/storage/mongodb/utils.py b/zaqar/storage/mongodb/utils.py
index b2d711fdf..198808c30 100644
--- a/zaqar/storage/mongodb/utils.py
+++ b/zaqar/storage/mongodb/utils.py
@@ -87,8 +87,6 @@ def calculate_backoff(attempt, max_attempts, max_sleep, max_jitter=0):
         the interval [0, max_sleep), determined linearly according to
         the ratio attempt / max_attempts, with optional jitter.
     """
-    if max_attempts < 0:
-        raise ValueError(u'max_attempts must be >= 0')
 
     if max_sleep < 0:
         raise ValueError(u'max_sleep must be >= 0')
diff --git a/zaqar/tests/unit/storage/test_impl_mongodb.py b/zaqar/tests/unit/storage/test_impl_mongodb.py
index abc635931..6e902cbec 100644
--- a/zaqar/tests/unit/storage/test_impl_mongodb.py
+++ b/zaqar/tests/unit/storage/test_impl_mongodb.py
@@ -110,8 +110,6 @@ class MongodbUtilsTest(MongodbSetupMixin, testing.TestBase):
         self.assertRaises(ValueError, utils.calculate_backoff, 0, 10, -2, 0)
         self.assertRaises(ValueError, utils.calculate_backoff, 0, 10, 2, -1)
 
-        self.assertRaises(ValueError, utils.calculate_backoff, -2, -10, 2, 0)
-        self.assertRaises(ValueError, utils.calculate_backoff, 2, -10, 2, 0)
         self.assertRaises(ValueError, utils.calculate_backoff, -2, 10, 2, 0)
         self.assertRaises(ValueError, utils.calculate_backoff, -1, 10, 2, 0)
         self.assertRaises(ValueError, utils.calculate_backoff, 10, 10, 2, 0)