diff --git a/osh/cmd_parse.py b/osh/cmd_parse.py
@@ -10,8 +10,6 @@
 cmd_parse.py - Parse high level shell commands.
 """

-import sys
-
 from asdl import const

 from core import braces
diff --git a/osh/cmd_parse_test.py b/osh/cmd_parse_test.py
@@ -6,11 +6,8 @@
 import sys
 import unittest

-from asdl import py_meta
-
 from core import ui
 from core.id_kind import Id
-from core.alloc import Pool
 from core import word
 from core import test_lib

diff --git a/osh/lex.py b/osh/lex.py
@@ -103,10 +103,10 @@
 import re

 from core.id_kind import Id, Kind, ID_SPEC
-from core import util
 from core.lexer import C, R

 from osh import ast_ as ast
+
 lex_mode_e = ast.lex_mode_e


diff --git a/osh/lex_test.py b/osh/lex_test.py
@@ -5,9 +5,8 @@

 import unittest

-from core import alloc
 from core.id_kind import Id, Kind, LookupKind
-from core.lexer import CompileAll, Lexer, LineLexer
+from core.lexer import CompileAll, LineLexer
 from core import test_lib

 from osh import parse_lib
diff --git a/osh/parse_lib.py b/osh/parse_lib.py
@@ -2,8 +2,6 @@
 parse_lib.py - Consolidate various parser instantiations here.
 """

-import sys
-
 from core import lexer
 from core import reader
 from core import id_kind
diff --git a/osh/word_parse.py b/osh/word_parse.py
@@ -429,9 +429,7 @@ def _ReadBracedBracedVarSub(self, d_quoted=False):
    self._Next(lex_mode_e.VS_1)
    self._Peek()

-    debug_token = self.cur_token
    ty = self.token_type
-    #print("T", debug_token)

    if ty == Id.VSub_Pound:
      # Disambiguate
diff --git a/osh/word_parse_test.py b/osh/word_parse_test.py
@@ -15,8 +15,8 @@

 from core import alloc
 from core.id_kind import Id
-from core import word
 from core import test_lib
+from core import word

 from osh import ast_ as ast
 from osh import parse_lib
@@ -491,8 +491,6 @@ def testMultiLine(self):
    test_lib.AssertAsdlEqual(self, ast.TokenWord(t), w)

  def testParseErrorLocation(self):
-    from core import word
-
    w = _assertSpanForWord(self, 'a=(1 2 3)')

    w = _assertSpanForWord(self, 'foo')
diff --git a/test/lint.sh b/test/lint.sh
@@ -99,12 +99,19 @@ bin-flake8() {

 flake8-all() {
  local -a dirs=(asdl bin core osh)
-  # stop the build if there are Python syntax errors or undefined names
+
+  # Step 1: Stop the build if there are Python syntax errors or undefined names
  bin-flake8 "${dirs[@]}" \
-    --count --select=E901,E999,F821,F822,F823 --show-source --statistics
+    --count --select=E901,E999,F821,F822,F823,F401 --show-source --statistics
+
+  # Step 2: Style errors as warnings.
+  local ignored='E125,E701,E241,E121,E111,E114,E128,E262,E226,E302,E265,E290,E202,E203,C901'
+  # trailing whitespace, line too long, blank lines
+  local ignored_for_now='W291,E501,E303'

  # exit-zero treats all errors as warnings.  The GitHub editor is 127 chars wide
  bin-flake8 "${dirs[@]}" \
+    --ignore="$ignored,$ignored_for_now" \
    --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
 }