--- a/.flake8
+++ b/.flake8
@@ -88,42 +88,45 @@ exclude =
     tools/crashreporter/*.configure,
     .ycm_extra_conf.py,
 
 # See:
 #   - http://flake8.pycqa.org/en/latest/user/error-codes.html
 #   - http://pep8.readthedocs.io/en/latest/intro.html#configuration
 ignore =
     # These should be triaged and either fixed or moved to the list below.
-    F633, F811, E117, W504, W605, W606,
+    F811, E117, W504, W605, W606,
     # These are intentionally disabled (not necessarily for good reason).
     #   F723: syntax error in type comment
     #       text contains quotes which breaks our custom JSON formatter
     F723, E121, E123, E126, E129, E133, E226, E241, E242, E402, E704, E741, W503,
 
 per-file-ignores =
     ipc/ipdl/*: F403, F405
     # cpp_eclipse has a lot of multi-line embedded XML which exceeds line length
     python/mozbuild/mozbuild/backend/cpp_eclipse.py: E501
     testing/firefox-ui/**/__init__.py: F401
     testing/marionette/**/__init__.py: F401
     testing/mozharness/configs/*: E124, E127, E128, E131, E231, E261, E265, E266, E501, W391
 
     # These paths contain Python-2 only syntax which cause errors since flake8
     # is run with Python 3.
-    build/**: F821
-    config/**: F821
-    js/**: F821
+    browser/app/macversion.py: F633
+    build/**: F633, F821
+    config/**: F633, F821
+    ipc/pull-chromium.py: F633
+    js/**: F633, F821
     memory/**: F821
     mozglue/**: F821
     python/mozbuild/**: F821
     python/mozversioncontrol/**: F821
     taskcluster/**: F821
     testing/mozharness/**: F821
     testing/raptor/**: F821
     testing/talos/**: F821
     toolkit/components/telemetry/**: F821
     tools/tryselect/**: F821
     testing/firefox-ui/tests/functional/safebrowsing/test_initial_download.py: F821
+    testing/gtest/rungtests.py: F633
     testing/marionette/**: F821
     testing/mochitest/**: F821
-    testing/xpcshell/**: F821
-    xpcom/idl-parser/xpidl/**: F821
+    testing/xpcshell/**: F633, F821
+    xpcom/idl-parser/xpidl/**: F633, F821