diff --git a/lib/matplotlib/tests/test_mlab.py b/lib/matplotlib/tests/test_mlab.py
index 01cacb13e6e9..b2265c3cb35d 100644
--- a/lib/matplotlib/tests/test_mlab.py
+++ b/lib/matplotlib/tests/test_mlab.py
@@ -2,7 +2,6 @@
 
 from numpy.testing import (assert_allclose, assert_almost_equal,
                            assert_array_equal, assert_array_almost_equal_nulp)
-import numpy.ma.testutils as matest
 import numpy as np
 import datetime as datetime
 import pytest
diff --git a/lib/matplotlib/tests/test_png.py b/lib/matplotlib/tests/test_png.py
index 508b46542885..d7e972843251 100644
--- a/lib/matplotlib/tests/test_png.py
+++ b/lib/matplotlib/tests/test_png.py
@@ -7,8 +7,6 @@
 from matplotlib.testing.decorators import image_comparison
 from matplotlib import pyplot as plt
 import matplotlib.cm as cm
-import sys
-on_win = (sys.platform == 'win32')
 
 
 @image_comparison(baseline_images=['pngsuite'], extensions=['png'],
diff --git a/lib/matplotlib/tests/test_triangulation.py b/lib/matplotlib/tests/test_triangulation.py
index c5c4bf78ed78..19d9fdac1030 100644
--- a/lib/matplotlib/tests/test_triangulation.py
+++ b/lib/matplotlib/tests/test_triangulation.py
@@ -1,16 +1,14 @@
 import numpy as np
-import matplotlib.pyplot as plt
-import matplotlib.tri as mtri
-import pytest
-from numpy.testing import assert_array_equal, assert_array_almost_equal,\
-    assert_array_less
+from numpy.testing import (
+    assert_array_equal, assert_array_almost_equal, assert_array_less)
 import numpy.ma.testutils as matest
-from matplotlib.testing.decorators import image_comparison
+import pytest
+
 import matplotlib.cm as cm
+import matplotlib.pyplot as plt
+import matplotlib.tri as mtri
 from matplotlib.path import Path
-
-import sys
-on_win = (sys.platform == 'win32')
+from matplotlib.testing.decorators import image_comparison
 
 
 def test_delaunay():
@@ -729,8 +727,7 @@ def z(x, y):
         dic_interp = {'lin': linear_interp,
                       'min_E': cubic_min_E,
                       'geom': cubic_geom}
-        # Testing that the interpolation is invariant by expansion along
-        # 1 axis...
+        # Test that the interpolation is invariant by expansion along 1 axis...
         for interp_key in ['lin', 'min_E', 'geom']:
             interpz = dic_interp[interp_key](xs, ys)
             matest.assert_array_almost_equal(interpz, interp_z0[interp_key])