diff --git a/letsencrypt/tests/display/ops_test.py b/letsencrypt/tests/display/ops_test.py
index 31db47cce..d98afe180 100644
--- a/letsencrypt/tests/display/ops_test.py
+++ b/letsencrypt/tests/display/ops_test.py
@@ -407,10 +407,11 @@ class ChooseNamesTest(unittest.TestCase):
                                           "uniçodé.com")
         self.assertEqual(_choose_names_manually(), [])
         # IDN exception with previous mocks
-        with mock.patch("letsencrypt.display.util") as mock_sl:
-            uerror = UnicodeEncodeError('mock', u'',
-                                        0, 1, 'mock')
-            mock_sl.separate_list_input.side_effect = uerror
+        with mock.patch(
+                "letsencrypt.display.ops.display_util.separate_list_input"
+        ) as mock_sli:
+            unicode_error = UnicodeEncodeError('mock', u'', 0, 1, 'mock')
+            mock_sli.side_effect = unicode_error
             self.assertEqual(_choose_names_manually(), [])
         # Punycode and no retry
         mock_util().input.return_value = (display_util.OK,