diff --git a/au_test_harness/cros_au_test_harness.py b/au_test_harness/cros_au_test_harness.py
index 8479726..a1a66d0 100755
--- a/au_test_harness/cros_au_test_harness.py
+++ b/au_test_harness/cros_au_test_harness.py
@@ -17,8 +17,6 @@
 import pickle
 import sys
 import tempfile
-import traceback
-import StringIO
 import unittest
 
 # TODO(sosa): Migrate to chromite cros_build_lib.
@@ -39,13 +37,14 @@
 
 class _LessBacktracingTestResult(unittest._TextTestResult):
   """TestResult class that suppresses stacks for AssertionError."""
+  # pylint: disable=W0212
   def addFailure(self, test, err):
     """Overrides unittest.TestCase.addFailure to suppress stack traces."""
-    exc_type, exc_value = err[:2]
+    exc_type = err[0]
     if exc_type is AssertionError:  # There's already plenty of debug output.
       self.failures.append((test, ''))
     else:
-      super(AUTest, self).addFailure(test, err)
+      super(_LessBacktracingTestResult, self).addFailure(test, err)
 
 
 class _LessBacktracingTestRunner(unittest.TextTestRunner):
diff --git a/bootperf-bin/perfprinter.py b/bootperf-bin/perfprinter.py
index d610714..4d33ddf 100644
--- a/bootperf-bin/perfprinter.py
+++ b/bootperf-bin/perfprinter.py
@@ -4,11 +4,6 @@
 
 """Routines for printing boot time performance test results."""
 
-import fnmatch
-import os
-import os.path
-import re
-
 import resultset
 
 
@@ -38,11 +33,11 @@
       keytype == resultset.TestResultSet.FIRMWARE_KEYSET):
     header = "%5s %3s  %5s %3s  %s" % (
         "time", "s%", "dt", "s%", "event")
-    format = "%5s %2d%%  %5s %2d%%  %s"
+    tformat = "%5s %2d%%  %5s %2d%%  %s"
   else:
     header = "%7s %3s  %7s %3s  %s" % (
         "diskrd", "s%", "delta", "s%", "event")
-    format = "%7s %2d%%  %7s %2d%%  %s"
+    tformat = "%7s %2d%%  %7s %2d%%  %s"
   havedata = False
   for dir_ in dirlist:
     results = reader(dir_)
@@ -70,7 +65,7 @@
       (valstring, val_printed) = keyset.PrintableStatistic(valueavg)
       delta = val_printed - prevvalue
       (deltastring, _) = keyset.PrintableStatistic(delta)
-      print format % (valstring, valuepct, "+" + deltastring, deltapct, stat)
+      print tformat % (valstring, valuepct, "+" + deltastring, deltapct, stat)
       prevvalue = val_printed
       prevstat = stat
     havedata = True
diff --git a/cros_gestures/cros_gestures_logging.py b/cros_gestures/cros_gestures_logging.py
index 04ac1e7..95c7814 100644
--- a/cros_gestures/cros_gestures_logging.py
+++ b/cros_gestures/cros_gestures_logging.py
@@ -10,7 +10,6 @@
 """
 
 import logging
-import sys
 
 import cros_gestures_constants
 
diff --git a/lib/dev_server_wrapper.py b/lib/dev_server_wrapper.py
index 595fd99..d51fafd 100644
--- a/lib/dev_server_wrapper.py
+++ b/lib/dev_server_wrapper.py
@@ -7,6 +7,7 @@
 
 import os
 import threading
+import sys
 import time
 
 import cros_build_lib as cros_lib
diff --git a/lib/parallel_test_job.py b/lib/parallel_test_job.py
index 4732369..e0d1df7 100644
--- a/lib/parallel_test_job.py
+++ b/lib/parallel_test_job.py
@@ -5,7 +5,6 @@
 """Module containing methods/classes related to running parallel test jobs."""
 
 import multiprocessing
-import sys
 import time
 
 import cros_build_lib as cros_lib
diff --git a/lib/test_helper.py b/lib/test_helper.py
index 46cad8b..79377cd 100644
--- a/lib/test_helper.py
+++ b/lib/test_helper.py
@@ -50,7 +50,7 @@
   """
   vm_image_path = '%s/chromiumos_qemu_image.bin' % os.path.dirname(image)
   if not os.path.exists(vm_image_path):
-    logging.info('Creating %s' % vm_image_path)
+    logging.info('Creating %s', vm_image_path)
     cros_build_lib.RunCommand(
         ['./image_to_vm.sh',
          '--full',