diff --git a/q2_quality_filter/tests/test_filter.py b/q2_quality_filter/tests/test_filter.py
index ff1fecc..76ebce4 100644
--- a/q2_quality_filter/tests/test_filter.py
+++ b/q2_quality_filter/tests/test_filter.py
@@ -80,7 +80,7 @@ def test_find_low_quality_window(self):
         obs = _find_low_quality_window(
             quality_scores, phred_offset=33, min_quality=44, window_length=2
         )
-
+self.assertEqual(obs, None)
         # test windows detected correctly
         # quality scores: M => 44; + => 10
         quality_scores = b'MMM++MM'