diff --git a/tests/utils/test_general.py b/tests/utils/test_general.py
index 4f469caf..9d3e10a8 100644
--- a/tests/utils/test_general.py
+++ b/tests/utils/test_general.py
@@ -255,7 +255,7 @@ def test_sort_dir_spectrum(self, galaxy, class_, expected):
         spec = spax.flux
 
         dir_ = _sort_dir(spec, class_)
-        dir_public = [it for it in dir_ if it[0] is not '_']
+        dir_public = [it for it in dir_ if it[0] != '_']
         assert set(dir_public) == set(expected)