diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index f9747fa1f6..2a3b61f7c3 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -78,9 +78,16 @@ def _CheckChangeHasEol(input_api, output_api, source_file_filter=None):
 
 def _PythonChecks(input_api, output_api):
   """Run checks on any modified Python files."""
-  pylint_disabled_files = (
-      'infra/bots/recipes.py',
-  )
+  blacklist = [
+      r'infra[\\\/]bots[\\\/]recipes.py',
+
+      # Blacklist DEPS. Those under third_party are already covered by
+      # input_api.DEFAULT_BLACK_LIST.
+      r'common[\\\/].*',
+      r'buildtools[\\\/].*',
+  ]
+  blacklist.extend(input_api.DEFAULT_BLACK_LIST)
+
   pylint_disabled_warnings = (
       'F0401',  # Unable to import.
       'E0611',  # No name in module.
@@ -92,18 +99,10 @@ def _PythonChecks(input_api, output_api):
       'W0613',  # Unused argument.
       'W0105',  # String statement has no effect.
   )
-  # Run Pylint on only the modified python files. Unfortunately it still runs
-  # Pylint on the whole file instead of just the modified lines.
-  affected_python_files = []
-  for affected_file in input_api.AffectedSourceFiles(None):
-    affected_file_path = affected_file.LocalPath()
-    if affected_file_path.endswith('.py'):
-      if affected_file_path not in pylint_disabled_files:
-        affected_python_files.append(affected_file_path)
   return input_api.canned_checks.RunPylint(
       input_api, output_api,
       disabled_warnings=pylint_disabled_warnings,
-      white_list=affected_python_files)
+      black_list=blacklist)
 
 
 def _JsonChecks(input_api, output_api):
diff --git a/tools/copyright/main.py b/tools/copyright/main.py
index 24969a7ac5..e428448d21 100644
--- a/tools/copyright/main.py
+++ b/tools/copyright/main.py
@@ -67,7 +67,7 @@ def GetAllFilepaths(root_directory):
     @param root_directory root directory within which to find all files
     """
     path_list = []
-    for dirpath, dirnames, filenames in os.walk(root_directory):
+    for dirpath, _, filenames in os.walk(root_directory):
         for filename in filenames:
             path_list.append(os.path.abspath(os.path.join(dirpath, filename)))
     return path_list
diff --git a/tools/jsondiff.py b/tools/jsondiff.py
index 91e3e4b743..ed4731ad3a 100755
--- a/tools/jsondiff.py
+++ b/tools/jsondiff.py
@@ -130,7 +130,8 @@ class GMDiffer(object):
             if results_of_this_type:
                 for test_name in results_of_this_type.keys():
                     digest_pair = results_of_this_type[test_name]
-                    if digest_pair[0] != gm_json.JSONKEY_HASHTYPE_BITMAP_64BITMD5:
+                    if (digest_pair[0] !=
+                            gm_json.JSONKEY_HASHTYPE_BITMAP_64BITMD5):
                         raise ValueError(
                             'test %s has unsupported hashtype %s' % (
                                 test_name, digest_pair[0]))
@@ -138,7 +139,7 @@ class GMDiffer(object):
         return result_dict
 
     def _DictionaryDiff(self, old_dict, new_dict):
-        """Generate a dictionary showing the diffs between old_dict and new_dict.
+        """Generate a dictionary showing diffs between old_dict and new_dict.
         Any entries which are identical across them will be left out."""
         diff_dict = {}
         all_keys = set(old_dict.keys() + new_dict.keys())
@@ -158,8 +159,9 @@ class GMDiffer(object):
         If newfile is not specified, then 'new' is the actual results within
         oldfile.
         """
-        return self.GenerateDiffDictFromStrings(self._GetFileContentsAsString(oldfile),
-                                                self._GetFileContentsAsString(newfile))
+        return self.GenerateDiffDictFromStrings(
+            self._GetFileContentsAsString(oldfile),
+            self._GetFileContentsAsString(newfile))
 
     def GenerateDiffDictFromStrings(self, oldjson, newjson=None):
         """Generate a dictionary showing the diffs: