diff --git a/scripts/update_payload/__init__.py b/scripts/update_payload/__init__.py
index 1906a16..e4a5588 100644
--- a/scripts/update_payload/__init__.py
+++ b/scripts/update_payload/__init__.py
@@ -5,7 +5,6 @@
 """Library for processing, verifying and applying Chrome OS update payloads."""
 
 # Just raise the interface classes to the root namespace.
-# pylint: disable=W0401
-from checker import CHECKS_TO_DISABLE
-from error import PayloadError
-from payload import Payload
+from update_payload.checker import CHECKS_TO_DISABLE
+from update_payload.error import PayloadError
+from update_payload.payload import Payload
diff --git a/scripts/update_payload/applier.py b/scripts/update_payload/applier.py
index 3cb9741..e470ac4 100644
--- a/scripts/update_payload/applier.py
+++ b/scripts/update_payload/applier.py
@@ -24,8 +24,8 @@
 import sys
 import tempfile
 
-import common
-from error import PayloadError
+from update_payload import common
+from update_payload.error import PayloadError
 
 
 #
@@ -44,7 +44,6 @@
     PayloadError if computed hash doesn't match expected one, or if fails to
     read the specified length of data.
   """
-  # pylint: disable=E1101
   hasher = hashlib.sha256()
   block_length = 1024 * 1024
   max_length = length if length >= 0 else sys.maxint
@@ -316,6 +315,7 @@
     base_name = '%s.dst_extents' % op_name
 
     # Iterate over the extents and write zero.
+    # pylint: disable=unused-variable
     for ex, ex_name in common.ExtentIter(op.dst_extents, base_name):
       # Only do actual writing if this is not a pseudo-extent.
       if ex.start_block != common.PSEUDO_EXTENT_MARKER:
@@ -361,6 +361,7 @@
     """
 
     length = 0
+    # pylint: disable=unused-variable
     for ex, ex_name in common.ExtentIter(extents, base_name):
       length += ex.num_blocks * self.block_size
     return length
diff --git a/scripts/update_payload/block_tracer.py b/scripts/update_payload/block_tracer.py
index f222b21..5caf7e3 100644
--- a/scripts/update_payload/block_tracer.py
+++ b/scripts/update_payload/block_tracer.py
@@ -16,7 +16,7 @@
 
 from __future__ import print_function
 
-import common
+from update_payload import common
 
 
 #
diff --git a/scripts/update_payload/checker.py b/scripts/update_payload/checker.py
index c710c47..e4cb845 100644
--- a/scripts/update_payload/checker.py
+++ b/scripts/update_payload/checker.py
@@ -21,11 +21,11 @@
 import os
 import subprocess
 
-import common
-import error
-import format_utils
-import histogram
-import update_metadata_pb2
+from update_payload import common
+from update_payload import error
+from update_payload import format_utils
+from update_payload import histogram
+from update_payload import update_metadata_pb2
 
 
 #
@@ -970,8 +970,6 @@
             op_name)
 
       # Check: Hash verifies correctly.
-      # pylint cannot find the method in hashlib, for some reason.
-      # pylint: disable=E1101
       actual_hash = hashlib.sha256(self.payload.ReadDataBlob(data_offset,
                                                              data_length))
       if op.data_sha256_hash != actual_hash.digest():
@@ -1168,8 +1166,6 @@
     report.AddSection('signatures')
 
     # Check: At least one signature present.
-    # pylint cannot see through the protobuf object, it seems.
-    # pylint: disable=E1101
     if not sigs.signatures:
       raise error.PayloadError('Signature block is empty.')
 
diff --git a/scripts/update_payload/checker_unittest.py b/scripts/update_payload/checker_unittest.py
index 245da55..974519d 100755
--- a/scripts/update_payload/checker_unittest.py
+++ b/scripts/update_payload/checker_unittest.py
@@ -20,14 +20,16 @@
 # pylint: disable=F0401
 import mox
 
-import checker
-import common
-import payload as update_payload  # Avoid name conflicts later.
-import test_utils
-import update_metadata_pb2
+from update_payload import checker
+from update_payload import common
+from update_payload import test_utils
+from update_payload import update_metadata_pb2
+from update_payload.error import PayloadError
+from update_payload.payload import Payload # Avoid name conflicts later.
 
 
 def _OpTypeByName(op_name):
+  """Returns the type of an operation from itsname."""
   op_name_to_type = {
       'REPLACE': common.OpType.REPLACE,
       'REPLACE_BZ': common.OpType.REPLACE_BZ,
@@ -55,7 +57,7 @@
   payload_file = cStringIO.StringIO()
   payload_gen_write_to_file_func(payload_file, **payload_gen_dargs)
   payload_file.seek(0)
-  payload = update_payload.Payload(payload_file)
+  payload = Payload(payload_file)
   payload.Init()
   return checker.PayloadChecker(payload, **checker_init_dargs)
 
@@ -65,7 +67,7 @@
   payload_file = cStringIO.StringIO()
   payload_gen.WriteToFile(payload_file)
   payload_file.seek(0)
-  payload = update_payload.Payload(payload_file)
+  payload = Payload(payload_file)
   payload.Init()
   return checker.PayloadChecker(payload)
 
@@ -91,7 +93,7 @@
 
   def MockPayload(self):
     """Create a mock payload object, complete with a mock manifest."""
-    payload = self.mox.CreateMock(update_payload.Payload)
+    payload = self.mox.CreateMock(Payload)
     payload.is_init = True
     payload.manifest = self.mox.CreateMock(
         update_metadata_pb2.DeltaArchiveManifest)
@@ -195,7 +197,7 @@
     args = (msg, name, report, is_mandatory, is_submsg)
     kwargs = {'convert': convert, 'linebreak': linebreak, 'indent': indent}
     if is_mandatory and not is_present:
-      self.assertRaises(update_payload.PayloadError,
+      self.assertRaises(PayloadError,
                         checker.PayloadChecker._CheckElem, *args, **kwargs)
     else:
       ret_val, ret_subreport = checker.PayloadChecker._CheckElem(*args,
@@ -229,8 +231,7 @@
 
     # Test the method call.
     if is_mandatory and not is_present:
-      self.assertRaises(update_payload.PayloadError, tested_func, *args,
-                        **kwargs)
+      self.assertRaises(PayloadError, tested_func, *args, **kwargs)
     else:
       ret_val = tested_func(*args, **kwargs)
       self.assertEquals(val if is_present else None, ret_val)
@@ -254,7 +255,7 @@
 
     # Test the method call.
     if is_mandatory and not is_present:
-      self.assertRaises(update_payload.PayloadError, tested_func, *args)
+      self.assertRaises(PayloadError, tested_func, *args)
     else:
       ret_val, ret_subreport = tested_func(*args)
       self.assertEquals(val if is_present else None, ret_val)
@@ -266,11 +267,9 @@
         None, None, 'foo', 'bar', 'baz'))
     self.assertIsNone(checker.PayloadChecker._CheckPresentIff(
         'a', 'b', 'foo', 'bar', 'baz'))
-    self.assertRaises(update_payload.PayloadError,
-                      checker.PayloadChecker._CheckPresentIff,
+    self.assertRaises(PayloadError, checker.PayloadChecker._CheckPresentIff,
                       'a', None, 'foo', 'bar', 'baz')
-    self.assertRaises(update_payload.PayloadError,
-                      checker.PayloadChecker._CheckPresentIff,
+    self.assertRaises(PayloadError, checker.PayloadChecker._CheckPresentIff,
                       None, 'b', 'foo', 'bar', 'baz')
 
   def DoCheckSha256SignatureTest(self, expect_pass, expect_subprocess_call,
@@ -299,7 +298,7 @@
         self.assertIsNone(checker.PayloadChecker._CheckSha256Signature(
             sig_data, 'foo', expected_signed_hash, 'bar'))
       else:
-        self.assertRaises(update_payload.PayloadError,
+        self.assertRaises(PayloadError,
                           checker.PayloadChecker._CheckSha256Signature,
                           sig_data, 'foo', expected_signed_hash, 'bar')
     finally:
@@ -359,31 +358,31 @@
 
   def testCheckBlocksFitLength_TooManyBlocks(self):
     """Tests _CheckBlocksFitLength(); fails due to excess blocks."""
-    self.assertRaises(update_payload.PayloadError,
+    self.assertRaises(PayloadError,
                       checker.PayloadChecker._CheckBlocksFitLength,
                       64, 5, 16, 'foo')
-    self.assertRaises(update_payload.PayloadError,
+    self.assertRaises(PayloadError,
                       checker.PayloadChecker._CheckBlocksFitLength,
                       60, 5, 16, 'foo')
-    self.assertRaises(update_payload.PayloadError,
+    self.assertRaises(PayloadError,
                       checker.PayloadChecker._CheckBlocksFitLength,
                       49, 5, 16, 'foo')
-    self.assertRaises(update_payload.PayloadError,
+    self.assertRaises(PayloadError,
                       checker.PayloadChecker._CheckBlocksFitLength,
                       48, 4, 16, 'foo')
 
   def testCheckBlocksFitLength_TooFewBlocks(self):
     """Tests _CheckBlocksFitLength(); fails due to insufficient blocks."""
-    self.assertRaises(update_payload.PayloadError,
+    self.assertRaises(PayloadError,
                       checker.PayloadChecker._CheckBlocksFitLength,
                       64, 3, 16, 'foo')
-    self.assertRaises(update_payload.PayloadError,
+    self.assertRaises(PayloadError,
                       checker.PayloadChecker._CheckBlocksFitLength,
                       60, 3, 16, 'foo')
-    self.assertRaises(update_payload.PayloadError,
+    self.assertRaises(PayloadError,
                       checker.PayloadChecker._CheckBlocksFitLength,
                       49, 3, 16, 'foo')
-    self.assertRaises(update_payload.PayloadError,
+    self.assertRaises(PayloadError,
                       checker.PayloadChecker._CheckBlocksFitLength,
                       48, 2, 16, 'foo')
 
@@ -476,8 +475,7 @@
                    fail_old_rootfs_fs_size or fail_new_kernel_fs_size or
                    fail_new_rootfs_fs_size)
     if should_fail:
-      self.assertRaises(update_payload.PayloadError,
-                        payload_checker._CheckManifest, report,
+      self.assertRaises(PayloadError, payload_checker._CheckManifest, report,
                         rootfs_part_size, kernel_part_size)
     else:
       self.assertIsNone(payload_checker._CheckManifest(report,
@@ -493,12 +491,10 @@
     self.assertIsNone(payload_checker._CheckLength(
         int(3.5 * block_size), 4, 'foo', 'bar'))
     # Fails, too few blocks.
-    self.assertRaises(update_payload.PayloadError,
-                      payload_checker._CheckLength,
+    self.assertRaises(PayloadError, payload_checker._CheckLength,
                       int(3.5 * block_size), 3, 'foo', 'bar')
     # Fails, too many blocks.
-    self.assertRaises(update_payload.PayloadError,
-                      payload_checker._CheckLength,
+    self.assertRaises(PayloadError, payload_checker._CheckLength,
                       int(3.5 * block_size), 5, 'foo', 'bar')
 
   def testCheckExtents(self):
@@ -533,30 +529,26 @@
     # Fails, extent missing a start block.
     extents = self.NewExtentList((-1, 4), (8, 3), (1024, 16))
     self.assertRaises(
-        update_payload.PayloadError, payload_checker._CheckExtents,
-        extents, (1024 + 16) * block_size, collections.defaultdict(int),
-        'foo')
+        PayloadError, payload_checker._CheckExtents, extents,
+        (1024 + 16) * block_size, collections.defaultdict(int), 'foo')
 
     # Fails, extent missing block count.
     extents = self.NewExtentList((0, -1), (8, 3), (1024, 16))
     self.assertRaises(
-        update_payload.PayloadError, payload_checker._CheckExtents,
-        extents, (1024 + 16) * block_size, collections.defaultdict(int),
-        'foo')
+        PayloadError, payload_checker._CheckExtents, extents,
+        (1024 + 16) * block_size, collections.defaultdict(int), 'foo')
 
     # Fails, extent has zero blocks.
     extents = self.NewExtentList((0, 4), (8, 3), (1024, 0))
     self.assertRaises(
-        update_payload.PayloadError, payload_checker._CheckExtents,
-        extents, (1024 + 16) * block_size, collections.defaultdict(int),
-        'foo')
+        PayloadError, payload_checker._CheckExtents, extents,
+        (1024 + 16) * block_size, collections.defaultdict(int), 'foo')
 
     # Fails, extent exceeds partition boundaries.
     extents = self.NewExtentList((0, 4), (8, 3), (1024, 16))
     self.assertRaises(
-        update_payload.PayloadError, payload_checker._CheckExtents,
-        extents, (1024 + 15) * block_size, collections.defaultdict(int),
-        'foo')
+        PayloadError, payload_checker._CheckExtents, extents,
+        (1024 + 15) * block_size, collections.defaultdict(int), 'foo')
 
   def testCheckReplaceOperation(self):
     """Tests _CheckReplaceOperation() where op.type == REPLACE."""
@@ -578,22 +570,19 @@
     # Fail, src extents founds.
     op.src_extents = ['bar']
     self.assertRaises(
-        update_payload.PayloadError,
-        payload_checker._CheckReplaceOperation,
+        PayloadError, payload_checker._CheckReplaceOperation,
         op, data_length, (data_length + block_size - 1) / block_size, 'foo')
 
     # Fail, missing data.
     op.src_extents = []
     self.assertRaises(
-        update_payload.PayloadError,
-        payload_checker._CheckReplaceOperation,
+        PayloadError, payload_checker._CheckReplaceOperation,
         op, None, (data_length + block_size - 1) / block_size, 'foo')
 
     # Fail, length / block number mismatch.
     op.src_extents = ['bar']
     self.assertRaises(
-        update_payload.PayloadError,
-        payload_checker._CheckReplaceOperation,
+        PayloadError, payload_checker._CheckReplaceOperation,
         op, data_length, (data_length + block_size - 1) / block_size + 1, 'foo')
 
   def testCheckReplaceBzOperation(self):
@@ -616,22 +605,19 @@
     # Fail, src extents founds.
     op.src_extents = ['bar']
     self.assertRaises(
-        update_payload.PayloadError,
-        payload_checker._CheckReplaceOperation,
+        PayloadError, payload_checker._CheckReplaceOperation,
         op, data_length, (data_length + block_size - 1) / block_size + 5, 'foo')
 
     # Fail, missing data.
     op.src_extents = []
     self.assertRaises(
-        update_payload.PayloadError,
-        payload_checker._CheckReplaceOperation,
+        PayloadError, payload_checker._CheckReplaceOperation,
         op, None, (data_length + block_size - 1) / block_size, 'foo')
 
     # Fail, too few blocks to justify BZ.
     op.src_extents = []
     self.assertRaises(
-        update_payload.PayloadError,
-        payload_checker._CheckReplaceOperation,
+        PayloadError, payload_checker._CheckReplaceOperation,
         op, data_length, (data_length + block_size - 1) / block_size, 'foo')
 
   def testCheckMoveOperation_Pass(self):
@@ -658,8 +644,7 @@
     self.AddToMessage(op.dst_extents,
                       self.NewExtentList((16, 128), (512, 6)))
     self.assertRaises(
-        update_payload.PayloadError,
-        payload_checker._CheckMoveOperation,
+        PayloadError, payload_checker._CheckMoveOperation,
         op, 1024, 134, 134, 'foo')
 
   def testCheckMoveOperation_FailInsufficientSrcBlocks(self):
@@ -673,8 +658,7 @@
     self.AddToMessage(op.dst_extents,
                       self.NewExtentList((16, 128), (512, 6)))
     self.assertRaises(
-        update_payload.PayloadError,
-        payload_checker._CheckMoveOperation,
+        PayloadError, payload_checker._CheckMoveOperation,
         op, None, 134, 134, 'foo')
 
   def testCheckMoveOperation_FailInsufficientDstBlocks(self):
@@ -688,8 +672,7 @@
     self.AddToMessage(op.dst_extents,
                       self.NewExtentList((16, 128), (512, 5)))
     self.assertRaises(
-        update_payload.PayloadError,
-        payload_checker._CheckMoveOperation,
+        PayloadError, payload_checker._CheckMoveOperation,
         op, None, 134, 134, 'foo')
 
   def testCheckMoveOperation_FailExcessSrcBlocks(self):
@@ -703,16 +686,14 @@
     self.AddToMessage(op.dst_extents,
                       self.NewExtentList((16, 128), (512, 5)))
     self.assertRaises(
-        update_payload.PayloadError,
-        payload_checker._CheckMoveOperation,
+        PayloadError, payload_checker._CheckMoveOperation,
         op, None, 134, 134, 'foo')
     self.AddToMessage(op.src_extents,
                       self.NewExtentList((1, 4), (12, 2), (1024, 129)))
     self.AddToMessage(op.dst_extents,
                       self.NewExtentList((16, 128), (512, 6)))
     self.assertRaises(
-        update_payload.PayloadError,
-        payload_checker._CheckMoveOperation,
+        PayloadError, payload_checker._CheckMoveOperation,
         op, None, 134, 134, 'foo')
 
   def testCheckMoveOperation_FailExcessDstBlocks(self):
@@ -726,8 +707,7 @@
     self.AddToMessage(op.dst_extents,
                       self.NewExtentList((16, 128), (512, 7)))
     self.assertRaises(
-        update_payload.PayloadError,
-        payload_checker._CheckMoveOperation,
+        PayloadError, payload_checker._CheckMoveOperation,
         op, None, 134, 134, 'foo')
 
   def testCheckMoveOperation_FailStagnantBlocks(self):
@@ -741,8 +721,7 @@
     self.AddToMessage(op.dst_extents,
                       self.NewExtentList((8, 128), (512, 6)))
     self.assertRaises(
-        update_payload.PayloadError,
-        payload_checker._CheckMoveOperation,
+        PayloadError, payload_checker._CheckMoveOperation,
         op, None, 134, 134, 'foo')
 
   def testCheckMoveOperation_FailZeroStartBlock(self):
@@ -756,8 +735,7 @@
     self.AddToMessage(op.dst_extents,
                       self.NewExtentList((8, 128), (512, 6)))
     self.assertRaises(
-        update_payload.PayloadError,
-        payload_checker._CheckMoveOperation,
+        PayloadError, payload_checker._CheckMoveOperation,
         op, None, 134, 134, 'foo')
 
     self.AddToMessage(op.src_extents,
@@ -765,8 +743,7 @@
     self.AddToMessage(op.dst_extents,
                       self.NewExtentList((0, 128), (512, 6)))
     self.assertRaises(
-        update_payload.PayloadError,
-        payload_checker._CheckMoveOperation,
+        PayloadError, payload_checker._CheckMoveOperation,
         op, None, 134, 134, 'foo')
 
   def testCheckAnyDiff(self):
@@ -780,14 +757,12 @@
 
     # Fail, missing data blob.
     self.assertRaises(
-        update_payload.PayloadError,
-        payload_checker._CheckAnyDiffOperation,
+        PayloadError, payload_checker._CheckAnyDiffOperation,
         op, None, 3, 'foo')
 
     # Fail, too big of a diff blob (unjustified).
     self.assertRaises(
-        update_payload.PayloadError,
-        payload_checker._CheckAnyDiffOperation,
+        PayloadError, payload_checker._CheckAnyDiffOperation,
         op, 10000, 2, 'foo')
 
   def testCheckSourceCopyOperation_Pass(self):
@@ -799,15 +774,13 @@
   def testCheckSourceCopyOperation_FailContainsData(self):
     """Tests _CheckSourceCopyOperation(); message contains data."""
     payload_checker = checker.PayloadChecker(self.MockPayload())
-    self.assertRaises(update_payload.PayloadError,
-                      payload_checker._CheckSourceCopyOperation,
+    self.assertRaises(PayloadError, payload_checker._CheckSourceCopyOperation,
                       134, 0, 0, 'foo')
 
   def testCheckSourceCopyOperation_FailBlockCountsMismatch(self):
     """Tests _CheckSourceCopyOperation(); src and dst block totals not equal."""
     payload_checker = checker.PayloadChecker(self.MockPayload())
-    self.assertRaises(update_payload.PayloadError,
-                      payload_checker._CheckSourceCopyOperation,
+    self.assertRaises(PayloadError, payload_checker._CheckSourceCopyOperation,
                       None, 0, 1, 'foo')
 
   def DoCheckOperationTest(self, op_type_name, is_last, allow_signature,
@@ -942,8 +915,7 @@
             old_part_size, new_part_size, prev_data_offset, allow_signature,
             blob_hash_counts)
     if should_fail:
-      self.assertRaises(update_payload.PayloadError,
-                        payload_checker._CheckOperation, *args)
+      self.assertRaises(PayloadError, payload_checker._CheckOperation, *args)
     else:
       self.assertEqual(op.data_length if op.HasField('data_length') else 0,
                        payload_checker._CheckOperation(*args))
@@ -965,6 +937,7 @@
     self.assertEqual(17, len(result))
 
   def DoCheckOperationsTest(self, fail_nonexhaustive_full_update):
+    """Tests _CheckOperations()."""
     # Generate a test payload. For this test, we only care about one
     # (arbitrary) set of operations, so we'll only be generating kernel and
     # test with them.
@@ -996,8 +969,7 @@
     args = (payload_checker.payload.manifest.install_operations, report, 'foo',
             0, rootfs_part_size, rootfs_part_size, rootfs_part_size, 0, False)
     if fail_nonexhaustive_full_update:
-      self.assertRaises(update_payload.PayloadError,
-                        payload_checker._CheckOperations, *args)
+      self.assertRaises(PayloadError, payload_checker._CheckOperations, *args)
     else:
       self.assertEqual(rootfs_data_length,
                        payload_checker._CheckOperations(*args))
@@ -1005,6 +977,7 @@
   def DoCheckSignaturesTest(self, fail_empty_sigs_blob, fail_missing_pseudo_op,
                             fail_mismatched_pseudo_op, fail_sig_missing_fields,
                             fail_unknown_sig_version, fail_incorrect_sig):
+    """Tests _CheckSignatures()."""
     # Generate a test payload. For this test, we only care about the signature
     # block and how it relates to the payload hash. Therefore, we're generating
     # a random (otherwise useless) payload for this purpose.
@@ -1069,8 +1042,7 @@
                    fail_unknown_sig_version or fail_incorrect_sig)
     args = (report, test_utils._PUBKEY_FILE_NAME)
     if should_fail:
-      self.assertRaises(update_payload.PayloadError,
-                        payload_checker._CheckSignatures, *args)
+      self.assertRaises(PayloadError, payload_checker._CheckSignatures, *args)
     else:
       self.assertIsNone(payload_checker._CheckSignatures(*args))
 
@@ -1099,7 +1071,7 @@
     if should_succeed:
       self.assertIsNone(payload_checker._CheckManifestMinorVersion(*args))
     else:
-      self.assertRaises(update_payload.PayloadError,
+      self.assertRaises(PayloadError,
                         payload_checker._CheckManifestMinorVersion, *args)
 
   def DoRunTest(self, rootfs_part_size_provided, kernel_part_size_provided,
@@ -1107,6 +1079,7 @@
                 fail_mismatched_block_size, fail_excess_data,
                 fail_rootfs_part_size_exceeded,
                 fail_kernel_part_size_exceeded):
+    """Tests Run()."""
     # Generate a test payload. For this test, we generate a full update that
     # has sample kernel and rootfs operations. Since most testing is done with
     # internal PayloadChecker methods that are tested elsewhere, here we only
@@ -1164,7 +1137,7 @@
             'assert_type': 'delta' if fail_wrong_payload_type else 'full',
             'block_size': use_block_size}}
     if fail_invalid_block_size:
-      self.assertRaises(update_payload.PayloadError, _GetPayloadChecker,
+      self.assertRaises(PayloadError, _GetPayloadChecker,
                         payload_gen.WriteToFileWithData, **kwargs)
     else:
       payload_checker = _GetPayloadChecker(payload_gen.WriteToFileWithData,
@@ -1178,8 +1151,7 @@
                      fail_rootfs_part_size_exceeded or
                      fail_kernel_part_size_exceeded)
       if should_fail:
-        self.assertRaises(update_payload.PayloadError, payload_checker.Run,
-                          **kwargs)
+        self.assertRaises(PayloadError, payload_checker.Run, **kwargs)
       else:
         self.assertIsNone(payload_checker.Run(**kwargs))
 
diff --git a/scripts/update_payload/common.py b/scripts/update_payload/common.py
index eaf0611..231c504 100644
--- a/scripts/update_payload/common.py
+++ b/scripts/update_payload/common.py
@@ -6,8 +6,8 @@
 
 from __future__ import print_function
 
-from error import PayloadError
-import update_metadata_pb2
+from update_payload import update_metadata_pb2
+from update_payload.error import PayloadError
 
 
 #
@@ -35,7 +35,6 @@
 class OpType(object):
   """Container for operation type constants."""
   _CLASS = update_metadata_pb2.InstallOperation
-  # pylint: disable=E1101
   REPLACE = _CLASS.REPLACE
   REPLACE_BZ = _CLASS.REPLACE_BZ
   MOVE = _CLASS.MOVE
diff --git a/scripts/update_payload/format_utils_unittest.py b/scripts/update_payload/format_utils_unittest.py
index 8c5ba8e..7153f9e 100755
--- a/scripts/update_payload/format_utils_unittest.py
+++ b/scripts/update_payload/format_utils_unittest.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python2
 #
 # Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
@@ -8,10 +8,11 @@
 
 import unittest
 
-import format_utils
+from update_payload import format_utils
 
 
 class NumToPercentTest(unittest.TestCase):
+  """ Tests number conversion to percentage format."""
   def testHundredPercent(self):
     self.assertEqual(format_utils.NumToPercent(1, 1), '100%')
 
@@ -43,6 +44,7 @@
 
 
 class BytesToHumanReadableTest(unittest.TestCase):
+  """ Tests number conversion to human readable format."""
   def testBaseTwo(self):
     self.assertEqual(format_utils.BytesToHumanReadable(0x1000), '4 KiB')
     self.assertEqual(format_utils.BytesToHumanReadable(0x400000), '4 MiB')
diff --git a/scripts/update_payload/histogram.py b/scripts/update_payload/histogram.py
index 9916329..f72db61 100644
--- a/scripts/update_payload/histogram.py
+++ b/scripts/update_payload/histogram.py
@@ -6,7 +6,7 @@
 
 from collections import defaultdict
 
-import format_utils
+from update_payload import format_utils
 
 
 class Histogram(object):
diff --git a/scripts/update_payload/histogram_unittest.py b/scripts/update_payload/histogram_unittest.py
index 421ff20..643bb32 100755
--- a/scripts/update_payload/histogram_unittest.py
+++ b/scripts/update_payload/histogram_unittest.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python2
 #
 # Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
@@ -8,11 +8,12 @@
 
 import unittest
 
-import format_utils
-import histogram
+from update_payload import format_utils
+from update_payload import histogram
 
 
 class HistogramTest(unittest.TestCase):
+  """ Tests histogram"""
 
   @staticmethod
   def AddHumanReadableSize(size):
diff --git a/scripts/update_payload/payload.py b/scripts/update_payload/payload.py
index 9450d02..8e50c1f 100644
--- a/scripts/update_payload/payload.py
+++ b/scripts/update_payload/payload.py
@@ -13,8 +13,8 @@
 from update_payload import block_tracer
 from update_payload import checker
 from update_payload import common
-from update_payload.error import PayloadError
 from update_payload import update_metadata_pb2
+from update_payload.error import PayloadError
 
 
 #
@@ -189,8 +189,6 @@
     if self.is_init:
       raise PayloadError('payload object already initialized')
 
-    # Initialize hash context.
-    # pylint: disable=E1101
     self.manifest_hasher = hashlib.sha256()
 
     # Read the file header.
@@ -232,11 +230,9 @@
         _DisplayIndentedValue('Build version', image_info.build_version)
 
     if self.manifest.HasField('old_image_info'):
-      # pylint: disable=E1101
       _DescribeImageInfo('Old Image', self.manifest.old_image_info)
 
     if self.manifest.HasField('new_image_info'):
-      # pylint: disable=E1101
       _DescribeImageInfo('New Image', self.manifest.new_image_info)
 
   def _AssertInit(self):
diff --git a/scripts/update_payload/test_utils.py b/scripts/update_payload/test_utils.py
index 61a91f5..38712fb 100644
--- a/scripts/update_payload/test_utils.py
+++ b/scripts/update_payload/test_utils.py
@@ -12,9 +12,9 @@
 import struct
 import subprocess
 
-import common
-import payload
-import update_metadata_pb2
+from update_payload import common
+from update_payload import payload
+from update_payload import update_metadata_pb2
 
 
 class TestError(Exception):
@@ -84,7 +84,6 @@
   Raises:
     TestError if something goes wrong.
   """
-  # pylint: disable=E1101
   data_sha256_hash = common.SIG_ASN1_HEADER + hashlib.sha256(data).digest()
   sign_cmd = ['openssl', 'rsautl', '-sign', '-inkey', privkey_file_name]
   try:
@@ -110,8 +109,6 @@
       version: signature version (None means do not assign)
       data: signature binary data (None means do not assign)
     """
-    # Pylint fails to identify a member of the Signatures message.
-    # pylint: disable=E1101
     sig = self.sigs.signatures.add()
     if version is not None:
       sig.version = version
@@ -174,11 +171,9 @@
       part_hash: the partition hash
     """
     if is_kernel:
-      # pylint: disable=E1101
       part_info = (self.manifest.new_kernel_info if is_new
                    else self.manifest.old_kernel_info)
     else:
-      # pylint: disable=E1101
       part_info = (self.manifest.new_rootfs_info if is_new
                    else self.manifest.old_rootfs_info)
     _SetMsgField(part_info, 'size', part_size)
@@ -188,7 +183,6 @@
                    data_length=None, src_extents=None, src_length=None,
                    dst_extents=None, dst_length=None, data_sha256_hash=None):
     """Adds an InstallOperation entry."""
-    # pylint: disable=E1101
     operations = (self.manifest.kernel_install_operations if is_kernel
                   else self.manifest.install_operations)
 
@@ -293,7 +287,6 @@
     data_offset = data_length = data_sha256_hash = None
     if data_blob is not None:
       if do_hash_data_blob:
-        # pylint: disable=E1101
         data_sha256_hash = hashlib.sha256(data_blob).digest()
       data_length, data_offset = self.AddData(data_blob)