diff --git a/oslo_utils/fixture.py b/oslo_utils/fixture.py
index 912d81bd..6a874de3 100644
--- a/oslo_utils/fixture.py
+++ b/oslo_utils/fixture.py
@@ -79,7 +79,7 @@ class _UUIDSentinels(object):
 
     def __getattr__(self, name):
         if name.startswith('_'):
-            raise ValueError('Sentinels must not start with _')
+            raise AttributeError('Sentinels must not start with _')
         with self._lock:
             if name not in self._sentinels:
                 self._sentinels[name] = uuidutils.generate_uuid()
diff --git a/oslo_utils/tests/test_fixture.py b/oslo_utils/tests/test_fixture.py
index dafac2f3..5775136d 100644
--- a/oslo_utils/tests/test_fixture.py
+++ b/oslo_utils/tests/test_fixture.py
@@ -80,5 +80,5 @@ class UUIDSentinelsTest(test_base.BaseTestCase):
         self.assertIsInstance(uuids.foo, str)
 
     def test_with_underline_prefix(self):
-        ex = self.assertRaises(ValueError, getattr, uuids, '_foo')
+        ex = self.assertRaises(AttributeError, getattr, uuids, '_foo')
         self.assertIn("Sentinels must not start with _", six.text_type(ex))