diff --git a/nova/tests/unit/test_filesystem.py b/nova/tests/unit/test_filesystem.py
index 5c3107472d..d7f91637a1 100644
--- a/nova/tests/unit/test_filesystem.py
+++ b/nova/tests/unit/test_filesystem.py
@@ -14,6 +14,8 @@ import io
 import os
 from unittest import mock
 
+import fixtures
+
 from nova import exception
 from nova import filesystem
 from nova import test
@@ -21,6 +23,10 @@ from nova import test
 
 class TestFSCommon(test.NoDBTestCase):
 
+    def setUp(self):
+        super().setUp()
+        self.useFixture(fixtures.MockPatch("time.sleep", mock.Mock()))
+
     def test_read_sys(self):
         open_mock = mock.mock_open(read_data='bar')
         with mock.patch('builtins.open', open_mock) as m_open: