diff --git a/.flake8 b/.flake8
index 7cc63f5822b0..1da5cbf5b3c7 100644
--- a/.flake8
+++ b/.flake8
@@ -8,7 +8,7 @@ ignore =
     E265, E266,
     E305, E306,
     E722, E741,
-    F811, F841,
+    F841,
     # Some new flake8 ignores:
     N801, N802, N803, N806, N812,
     # pydocstyle
@@ -50,7 +50,7 @@ per-file-ignores =
     lib/matplotlib/lines.py: F401
     lib/matplotlib/mathtext.py: E221, E251
     lib/matplotlib/pylab.py: F401, F403
-    lib/matplotlib/pyplot.py: F401
+    lib/matplotlib/pyplot.py: F401, F811
     lib/matplotlib/rcsetup.py: E501
     lib/matplotlib/style/__init__.py: F401
     lib/matplotlib/testing/conftest.py: F401
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
index 387dd9100fa0..85a846132899 100644
--- a/lib/matplotlib/axes/_axes.py
+++ b/lib/matplotlib/axes/_axes.py
@@ -7,12 +7,12 @@
 import numpy as np
 from numpy import ma
 
-import matplotlib.category as _  # <-registers a category unit converter
+import matplotlib.category  # Register category unit converter as side-effect.
 import matplotlib.cbook as cbook
 import matplotlib.collections as mcoll
 import matplotlib.colors as mcolors
 import matplotlib.contour as mcontour
-import matplotlib.dates as _  # <-registers a date unit converter
+import matplotlib.dates  # Register date unit converter as side-effect.
 import matplotlib.docstring as docstring
 import matplotlib.image as mimage
 import matplotlib.legend as mlegend
diff --git a/lib/matplotlib/pyplot.py b/lib/matplotlib/pyplot.py
index d16a5082887e..86638d5b1484 100644
--- a/lib/matplotlib/pyplot.py
+++ b/lib/matplotlib/pyplot.py
@@ -40,7 +40,6 @@
 from matplotlib.figure import Figure, figaspect
 from matplotlib.gridspec import GridSpec
 from matplotlib import rcParams, rcParamsDefault, get_backend, rcParamsOrig
-from matplotlib import rc_context
 from matplotlib.rcsetup import interactive_bk as _interactive_bk
 from matplotlib.artist import Artist
 from matplotlib.axes import Axes, Subplot
diff --git a/lib/matplotlib/spines.py b/lib/matplotlib/spines.py
index fa9a1a82c8fb..f364170bfe80 100644
--- a/lib/matplotlib/spines.py
+++ b/lib/matplotlib/spines.py
@@ -3,7 +3,6 @@
 import matplotlib
 from matplotlib import cbook, docstring, rcParams
 from matplotlib.artist import allow_rasterization
-import matplotlib.cbook as cbook
 import matplotlib.transforms as mtransforms
 import matplotlib.patches as mpatches
 import matplotlib.path as mpath