diff --git a/tests/unit/test_main.py b/tests/unit/test_main.py
index 6c5bef76c..59e224aed 100644
--- a/tests/unit/test_main.py
+++ b/tests/unit/test_main.py
@@ -592,8 +592,8 @@ def test_isort_with_stdin(capsys):
     out, error = capsys.readouterr()
 
     assert error
-    assert not "underlying stream is not seekable" in error
-    assert not "underlying stream is not seekable" in error
+    assert "underlying stream is not seekable" not in error
+    assert "underlying stream is not seekable" not in error
 
     # ensures that isort correctly sorts stdin with --ls flag
 
diff --git a/tests/unit/test_pylama_isort.py b/tests/unit/test_pylama_isort.py
index 035b5e31d..d3900c3f0 100644
--- a/tests/unit/test_pylama_isort.py
+++ b/tests/unit/test_pylama_isort.py
@@ -1,5 +1,3 @@
-import os
-
 from isort.pylama_isort import Linter