diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index f261e54..ccfdc4b 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -1,5 +1,5 @@
 -   repo: https://github.com/pre-commit/pre-commit-hooks
-    sha: 9ba5af45ce2d29b64c9a348a6fcff5553eea1f2c
+    sha: v0.7.0
     hooks:
     -   id: trailing-whitespace
     -   id: end-of-file-fixer
@@ -13,12 +13,16 @@
     -   id: requirements-txt-fixer
     -   id: flake8
 -   repo: https://github.com/pre-commit/pre-commit
-    sha: 8dba3281d5051060755459dcf88e28fc26c27526
+    sha: v0.12.2
     hooks:
     -   id: validate_config
     -   id: validate_manifest
 -   repo: https://github.com/asottile/reorder_python_imports
-    sha: 3d86483455ab5bd06cc1069fdd5ac57be5463f10
+    sha: v0.3.1
     hooks:
     -   id: reorder-python-imports
         language_version: python2.7
+-   repo: https://github.com/asottile/pyupgrade
+    sha: v1.0.0
+    hooks:
+    -   id: pyupgrade
diff --git a/.pre-commit-hooks.yaml b/.pre-commit-hooks.yaml
new file mode 100644
index 0000000..0604585
--- /dev/null
+++ b/.pre-commit-hooks.yaml
@@ -0,0 +1,149 @@
+-   id: autopep8-wrapper
+    name: autopep8 wrapper
+    description: "Runs autopep8 over python source.  If you configure additional arguments you'll want to at least include -i."
+    entry: autopep8-wrapper
+    language: python
+    files: \.py$
+    args: [-i]
+-   id: check-added-large-files
+    name: Check for added large files
+    description: Prevent giant files from being committed
+    entry: check-added-large-files
+    language: python
+    # Match all files
+    files: ''
+-   id: check-ast
+    name: Check python ast
+    description: Simply check whether the files parse as valid python.
+    entry: check-ast
+    language: python
+    files: '\.py$'
+-   id: check-byte-order-marker
+    name: Check for byte-order marker
+    description: Forbid files which have a UTF-8 byte-order marker
+    entry: check-byte-order-marker
+    language: python
+    files: '\.py$'
+-   id: check-case-conflict
+    name: Check for case conflicts
+    description: Check for files that would conflict in case-insensitive filesystems
+    entry: check-case-conflict
+    language: python
+    # Match all files
+    files: ''
+-   id: check-docstring-first
+    name: Check docstring is first
+    description: Checks a common error of defining a docstring after code.
+    entry: check-docstring-first
+    language: python
+    files: \.py$
+-   id: check-json
+    name: Check JSON
+    description: This hook checks json files for parseable syntax.
+    entry: check-json
+    language: python
+    files: \.json$
+-   id: pretty-format-json
+    name: Pretty format JSON
+    description: This hook sets a standard for formatting JSON files.
+    entry: pretty-format-json
+    language: python
+    files: \.json$
+-   id: check-merge-conflict
+    name: Check for merge conflicts
+    description: Check for files that contain merge conflict strings.
+    entry: check-merge-conflict
+    language: python
+    # Match all files
+    files: ''
+-   id: check-symlinks
+    name: Check for broken symlinks
+    description: Checks for symlinks which do not point to anything.
+    entry: check-symlinks
+    language: python
+    # Match all files
+    files: ''
+-   id: check-xml
+    name: Check Xml
+    description: This hook checks xml files for parseable syntax.
+    entry: check-xml
+    language: python
+    files: \.xml$
+-   id: check-yaml
+    name: Check Yaml
+    description: This hook checks yaml files for parseable syntax.
+    entry: check-yaml
+    language: python
+    files: \.(yaml|yml|eyaml)$
+-   id: debug-statements
+    name: Debug Statements (Python)
+    description: This hook checks that debug statements (pdb, ipdb, pudb) are not imported on commit.
+    entry: debug-statement-hook
+    language: python
+    files: \.py$
+-   id: detect-aws-credentials
+    name: Detect AWS Credentials
+    description: Detects *your* aws credentials from the aws cli credentials file
+    entry: detect-aws-credentials
+    language: python
+    files: ''
+-   id: detect-private-key
+    name: Detect Private Key
+    description: Detects the presence of private keys
+    entry: detect-private-key
+    language: python
+    files: ''
+-   id: double-quote-string-fixer
+    name: Fix double quoted strings
+    description: This hook replaces double quoted strings with single quoted strings
+    entry: double-quote-string-fixer
+    language: python
+    files: \.py$
+-   id: end-of-file-fixer
+    name: Fix End of Files
+    description: Ensures that a file is either empty, or ends with one newline.
+    entry: end-of-file-fixer
+    language: python
+    files: \.(asciidoc|adoc|coffee|cpp|css|c|ejs|erb|groovy|h|haml|hh|hpp|hxx|html|in|j2|jade|json|js|less|markdown|md|ml|mli|pp|py|rb|rs|R|scala|scss|sh|slim|tex|tmpl|ts|txt|yaml|yml)$
+-   id: fix-encoding-pragma
+    name: Fix python encoding pragma
+    language: python
+    entry: fix-encoding-pragma
+    description: 'Add # -*- coding: utf-8 -*- to the top of python files'
+    files: \.py$
+-   id: flake8
+    name: Flake8
+    description: This hook runs flake8.
+    entry: flake8
+    language: python
+    files: \.py$
+-   id: forbid-new-submodules
+    name: Forbid new submodules
+    language: python
+    entry: forbid-new-submodules
+    description: Prevent addition of new git submodules
+    files: ''
+-   id: name-tests-test
+    name: Tests should end in _test.py
+    description: This verifies that test files are named correctly
+    entry: name-tests-test
+    language: python
+    files: tests/.+\.py$
+-   id: pyflakes
+    name: Pyflakes (DEPRECATED, use flake8)
+    description: This hook runs pyflakes. (This is deprecated, use flake8).
+    entry: pyflakes
+    language: python
+    files: \.py$
+-   id: requirements-txt-fixer
+    name: Fix requirements.txt
+    description: Sorts entries in requirements.txt
+    entry: requirements-txt-fixer
+    language: python
+    files: requirements.*\.txt$
+-   id: trailing-whitespace
+    name: Trim Trailing Whitespace
+    description: This hook trims trailing whitespace.
+    entry: trailing-whitespace-fixer
+    language: python
+    files: \.(asciidoc|adoc|coffee|cpp|css|c|ejs|erb|groovy|h|haml|hh|hpp|hxx|html|in|j2|jade|json|js|less|markdown|md|ml|mli|pp|py|rb|rs|R|scala|scss|sh|slim|tex|tmpl|ts|txt|yaml|yml)$
diff --git a/.travis.yml b/.travis.yml
index 3bec92f..a3e5fc4 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,18 +1,19 @@
 language: python
-python: 3.5
-env: # These should match the tox env list
-    - TOXENV=py27
-    - TOXENV=py34
-    - TOXENV=py35
-    - TOXENV=pypy
+sudo: false
+matrix:
+    include:  # These should match the tox env list
+    -   env: TOXENV=py27
+    -   env: TOXENV=py35
+        python: 3.5
+    -   env: TOXENV=py36
+        python: 3.6
+    -   env: TOXENV=pypy
 install: pip install coveralls tox
 script: tox
 before_install:
   # Install git-lfs for a test
   - './get-git-lfs.py && export PATH="/tmp/git-lfs:$PATH"'
-after_success:
-    - coveralls
-sudo: false
+after_success: coveralls
 cache:
     directories:
         - $HOME/.cache/pip
diff --git a/CHANGELOG b/CHANGELOG
index b9f2331..c489206 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,12 @@
+0.7.1
+=====
+- Don't false positive on files where trailing whitespace isn't changed.
+
+0.7.0
+=====
+- Improve search for detecting aws keys
+- Add .pre-commit-hooks.yaml for forward compatibility
+
 0.6.1
 =====
 - trailing-whitespace-hook: restore original file on catastrophic failure
diff --git a/README.md b/README.md
index b68dd22..031edfd 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,5 @@
 [![Build Status](https://travis-ci.org/pre-commit/pre-commit-hooks.svg?branch=master)](https://travis-ci.org/pre-commit/pre-commit-hooks)
-[![Coverage Status](https://img.shields.io/coveralls/pre-commit/pre-commit-hooks.svg?branch=master)](https://coveralls.io/r/pre-commit/pre-commit-hooks)
+[![Coverage Status](https://coveralls.io/repos/github/pre-commit/pre-commit-hooks/badge.svg?branch=master)](https://coveralls.io/github/pre-commit/pre-commit-hooks?branch=master)
 [![Build status](https://ci.appveyor.com/api/projects/status/dfcpng35u4g0r0t1/branch/master?svg=true)](https://ci.appveyor.com/project/asottile/pre-commit-hooks/branch/master)
 
 pre-commit-hooks
@@ -15,7 +15,7 @@ See also: https://github.com/pre-commit/pre-commit
 Add this to your `.pre-commit-config.yaml`
 
     -   repo: git://github.com/pre-commit/pre-commit-hooks
-        sha: ''  # Use the sha you want to point at
+        sha: v0.7.1  # Use the ref you want to point at
         hooks:
         -   id: trailing-whitespace
         # -   id: ...
diff --git a/appveyor.yml b/appveyor.yml
index 4bde8cc..a0df40b 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -1,10 +1,10 @@
 environment:
     matrix:
         - TOXENV: py27
-        - TOXENV: py35
+        - TOXENV: py36
 
 install:
-    - "SET PATH=C:\\Python35;C:\\Python35\\Scripts;%PATH%"
+    - "SET PATH=C:\\Python36;C:\\Python36\\Scripts;%PATH%"
     - pip install tox
 
 # Not a C# project
diff --git a/get-git-lfs.py b/get-git-lfs.py
index 4897a56..c1f2197 100755
--- a/get-git-lfs.py
+++ b/get-git-lfs.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.4
+#!/usr/bin/env python3
 """This is a script to install git-lfs to a tempdir for use in tests"""
 import io
 import os.path
diff --git a/pre_commit_hooks/autopep8_wrapper.py b/pre_commit_hooks/autopep8_wrapper.py
index f6f55fb..52aaebe 100644
--- a/pre_commit_hooks/autopep8_wrapper.py
+++ b/pre_commit_hooks/autopep8_wrapper.py
@@ -17,7 +17,7 @@ def main(argv=None):
         original_contents = io.open(filename).read()
         new_contents = autopep8.fix_code(original_contents, args)
         if original_contents != new_contents:
-            print('Fixing {0}'.format(filename))
+            print('Fixing {}'.format(filename))
             retv = 1
             with io.open(filename, 'w') as output_file:
                 output_file.write(new_contents)
diff --git a/pre_commit_hooks/check_added_large_files.py b/pre_commit_hooks/check_added_large_files.py
index 5ef7f22..8d5f4c4 100644
--- a/pre_commit_hooks/check_added_large_files.py
+++ b/pre_commit_hooks/check_added_large_files.py
@@ -26,10 +26,10 @@ def lfs_files():
         assert mode in ('A', 'R')
         return filepart if mode == 'A' else filepart.split(' -> ')[1]
 
-    return set(
+    return {
         to_file_part(mode, filepart) for mode, filepart in modes_and_fileparts
         if mode in ('A', 'R')
-    )
+    }
 
 
 def find_large_added_files(filenames, maxkb):
@@ -41,7 +41,7 @@ def find_large_added_files(filenames, maxkb):
     for filename in filenames:
         kb = int(math.ceil(os.stat(filename).st_size / 1024))
         if kb > maxkb:
-            print('{0} ({1} KB) exceeds {2} KB.'.format(filename, kb, maxkb))
+            print('{} ({} KB) exceeds {} KB.'.format(filename, kb, maxkb))
             retv = 1
 
     return retv
diff --git a/pre_commit_hooks/check_ast.py b/pre_commit_hooks/check_ast.py
index c993e6a..169e077 100644
--- a/pre_commit_hooks/check_ast.py
+++ b/pre_commit_hooks/check_ast.py
@@ -22,10 +22,10 @@ def check_ast(argv=None):
         try:
             ast.parse(open(filename, 'rb').read(), filename=filename)
         except SyntaxError:
-            print('{0}: failed parsing with {1}:'.format(
+            print('{}: failed parsing with {}:'.format(
                 filename, interpreter,
             ))
-            print('\n{0}'.format(
+            print('\n{}'.format(
                 '    ' + traceback.format_exc().replace('\n', '\n    ')
             ))
             retval = 1
diff --git a/pre_commit_hooks/check_byte_order_marker.py b/pre_commit_hooks/check_byte_order_marker.py
index 274f949..1541b30 100644
--- a/pre_commit_hooks/check_byte_order_marker.py
+++ b/pre_commit_hooks/check_byte_order_marker.py
@@ -16,7 +16,7 @@ def main(argv=None):
         with open(filename, 'rb') as f:
             if f.read(3) == b'\xef\xbb\xbf':
                 retv = 1
-                print('{0}: Has a byte-order marker'.format(filename))
+                print('{}: Has a byte-order marker'.format(filename))
 
     return retv
 
diff --git a/pre_commit_hooks/check_case_conflict.py b/pre_commit_hooks/check_case_conflict.py
index dd4ad86..3d6cf74 100644
--- a/pre_commit_hooks/check_case_conflict.py
+++ b/pre_commit_hooks/check_case_conflict.py
@@ -9,7 +9,7 @@ from pre_commit_hooks.util import cmd_output
 
 
 def lower_set(iterable):
-    return set(x.lower() for x in iterable)
+    return {x.lower() for x in iterable}
 
 
 def find_conflicting_filenames(filenames):
@@ -35,7 +35,7 @@ def find_conflicting_filenames(filenames):
             if x.lower() in conflicts
         ]
         for filename in sorted(conflicting_files):
-            print('Case-insensitivity conflict found: {0}'.format(filename))
+            print('Case-insensitivity conflict found: {}'.format(filename))
         retv = 1
 
     return retv
diff --git a/pre_commit_hooks/check_docstring_first.py b/pre_commit_hooks/check_docstring_first.py
index da5425d..8e658a1 100644
--- a/pre_commit_hooks/check_docstring_first.py
+++ b/pre_commit_hooks/check_docstring_first.py
@@ -27,16 +27,16 @@ def check_docstring_first(src, filename='<unknown>'):
         if tok_type == tokenize.STRING and scol == 0:
             if found_docstring_line is not None:
                 print(
-                    '{0}:{1} Multiple module docstrings '
-                    '(first docstring on line {2}).'.format(
+                    '{}:{} Multiple module docstrings '
+                    '(first docstring on line {}).'.format(
                         filename, sline, found_docstring_line,
                     )
                 )
                 return 1
             elif found_code_line is not None:
                 print(
-                    '{0}:{1} Module docstring appears after code '
-                    '(code seen on line {2}).'.format(
+                    '{}:{} Module docstring appears after code '
+                    '(code seen on line {}).'.format(
                         filename, sline, found_code_line,
                     )
                 )
diff --git a/pre_commit_hooks/check_json.py b/pre_commit_hooks/check_json.py
index 688f719..e1578ff 100644
--- a/pre_commit_hooks/check_json.py
+++ b/pre_commit_hooks/check_json.py
@@ -16,7 +16,7 @@ def check_json(argv=None):
         try:
             simplejson.load(open(filename))
         except (simplejson.JSONDecodeError, UnicodeDecodeError) as exc:
-            print('{0}: Failed to json decode ({1})'.format(filename, exc))
+            print('{}: Failed to json decode ({})'.format(filename, exc))
             retval = 1
     return retval
 
diff --git a/pre_commit_hooks/check_symlinks.py b/pre_commit_hooks/check_symlinks.py
index 713dd83..fd80089 100644
--- a/pre_commit_hooks/check_symlinks.py
+++ b/pre_commit_hooks/check_symlinks.py
@@ -19,7 +19,7 @@ def check_symlinks(argv=None):
                 os.path.islink(filename) and
                 not os.path.exists(filename)
         ):  # pragma: no cover (symlink support required)
-            print('{0}: Broken symlink'.format(filename))
+            print('{}: Broken symlink'.format(filename))
             retv = 1
 
     return retv
diff --git a/pre_commit_hooks/check_xml.py b/pre_commit_hooks/check_xml.py
index 926f6e9..a4c11a5 100644
--- a/pre_commit_hooks/check_xml.py
+++ b/pre_commit_hooks/check_xml.py
@@ -19,7 +19,7 @@ def check_xml(argv=None):
             with io.open(filename, 'rb') as xml_file:
                 xml.sax.parse(xml_file, xml.sax.ContentHandler())
         except xml.sax.SAXException as exc:
-            print('{0}: Failed to xml parse ({1})'.format(filename, exc))
+            print('{}: Failed to xml parse ({})'.format(filename, exc))
             retval = 1
     return retval
 
diff --git a/pre_commit_hooks/debug_statement_hook.py b/pre_commit_hooks/debug_statement_hook.py
index 52fe72e..902198f 100644
--- a/pre_commit_hooks/debug_statement_hook.py
+++ b/pre_commit_hooks/debug_statement_hook.py
@@ -7,7 +7,7 @@ import collections
 import traceback
 
 
-DEBUG_STATEMENTS = set(['pdb', 'ipdb', 'pudb', 'q', 'rdb'])
+DEBUG_STATEMENTS = {'pdb', 'ipdb', 'pudb', 'q', 'rdb'}
 
 
 DebugStatement = collections.namedtuple(
@@ -37,7 +37,7 @@ def check_file_for_debug_statements(filename):
     try:
         ast_obj = ast.parse(open(filename).read(), filename=filename)
     except SyntaxError:
-        print('{0} - Could not parse ast'.format(filename))
+        print('{} - Could not parse ast'.format(filename))
         print()
         print('\t' + traceback.format_exc().replace('\n', '\n\t'))
         print()
@@ -47,7 +47,7 @@ def check_file_for_debug_statements(filename):
     if visitor.debug_import_statements:
         for debug_statement in visitor.debug_import_statements:
             print(
-                '{0}:{1}:{2} - {3} imported'.format(
+                '{}:{}:{} - {} imported'.format(
                     filename,
                     debug_statement.line,
                     debug_statement.col,
diff --git a/pre_commit_hooks/detect_aws_credentials.py b/pre_commit_hooks/detect_aws_credentials.py
index b0826ca..42758f0 100644
--- a/pre_commit_hooks/detect_aws_credentials.py
+++ b/pre_commit_hooks/detect_aws_credentials.py
@@ -95,6 +95,12 @@ def main(argv=None):
             'secret keys from'
         )
     )
+    parser.add_argument(
+        '--allow-missing-credentials',
+        dest='allow_missing_credentials',
+        action='store_true',
+        help='Allow hook to pass when no credentials are detected.'
+    )
     args = parser.parse_args(argv)
 
     credential_files = set(args.credential_files)
@@ -111,6 +117,9 @@ def main(argv=None):
     # the set of keys.
     keys |= get_aws_secrets_from_env()
 
+    if not keys and args.allow_missing_credentials:
+        return 0
+
     if not keys:
         print(
             'No AWS keys were found in the configured credential files and '
diff --git a/pre_commit_hooks/detect_private_key.py b/pre_commit_hooks/detect_private_key.py
index d187364..feb2208 100644
--- a/pre_commit_hooks/detect_private_key.py
+++ b/pre_commit_hooks/detect_private_key.py
@@ -26,7 +26,7 @@ def detect_private_key(argv=None):
 
     if private_key_files:
         for private_key_file in private_key_files:
-            print('Private key found: {0}'.format(private_key_file))
+            print('Private key found: {}'.format(private_key_file))
         return 1
     else:
         return 0
diff --git a/pre_commit_hooks/end_of_file_fixer.py b/pre_commit_hooks/end_of_file_fixer.py
index 3349d83..4fe82b7 100644
--- a/pre_commit_hooks/end_of_file_fixer.py
+++ b/pre_commit_hooks/end_of_file_fixer.py
@@ -58,7 +58,7 @@ def end_of_file_fixer(argv=None):
         with open(filename, 'rb+') as file_obj:
             ret_for_file = fix_file(file_obj)
             if ret_for_file:
-                print('Fixing {0}'.format(filename))
+                print('Fixing {}'.format(filename))
             retv |= ret_for_file
 
     return retv
diff --git a/pre_commit_hooks/pretty_format_json.py b/pre_commit_hooks/pretty_format_json.py
index 91dae8d..bf1ccb1 100644
--- a/pre_commit_hooks/pretty_format_json.py
+++ b/pre_commit_hooks/pretty_format_json.py
@@ -25,7 +25,7 @@ def _get_pretty_format(contents, indent, sort_keys=True, top_keys=[]):
 
 
 def _autofix(filename, new_contents):
-    print("Fixing file {0}".format(filename))
+    print("Fixing file {}".format(filename))
     with open(filename, 'w') as f:
         f.write(new_contents)
 
@@ -100,7 +100,7 @@ def pretty_format_json(argv=None):
             )
 
             if contents != pretty_contents:
-                print("File {0} is not pretty-formatted".format(json_file))
+                print("File {} is not pretty-formatted".format(json_file))
 
                 if args.autofix:
                     _autofix(json_file, pretty_contents)
@@ -109,7 +109,7 @@ def pretty_format_json(argv=None):
 
         except simplejson.JSONDecodeError:
             print(
-                "Input File {0} is not a valid JSON, consider using check-json"
+                "Input File {} is not a valid JSON, consider using check-json"
                 .format(json_file)
             )
             return 1
diff --git a/pre_commit_hooks/requirements_txt_fixer.py b/pre_commit_hooks/requirements_txt_fixer.py
index 64b5e47..efa1906 100644
--- a/pre_commit_hooks/requirements_txt_fixer.py
+++ b/pre_commit_hooks/requirements_txt_fixer.py
@@ -84,7 +84,7 @@ def fix_requirements_txt(argv=None):
             ret_for_file = fix_requirements(file_obj)
 
             if ret_for_file:
-                print('Sorting {0}'.format(arg))
+                print('Sorting {}'.format(arg))
 
             retv |= ret_for_file
 
diff --git a/pre_commit_hooks/string_fixer.py b/pre_commit_hooks/string_fixer.py
index 9ef7a37..3523e8a 100644
--- a/pre_commit_hooks/string_fixer.py
+++ b/pre_commit_hooks/string_fixer.py
@@ -69,7 +69,7 @@ def main(argv=None):
     for filename in args.filenames:
         return_value = fix_strings(filename)
         if return_value != 0:
-            print('Fixing strings in {0}'.format(filename))
+            print('Fixing strings in {}'.format(filename))
         retv |= return_value
 
     return retv
diff --git a/pre_commit_hooks/tests_should_end_in_test.py b/pre_commit_hooks/tests_should_end_in_test.py
index 4bfc767..5f9bbac 100644
--- a/pre_commit_hooks/tests_should_end_in_test.py
+++ b/pre_commit_hooks/tests_should_end_in_test.py
@@ -16,7 +16,7 @@ def validate_files(argv=None):
     args = parser.parse_args(argv)
 
     retcode = 0
-    test_name_pattern = 'test_.*.py' if args.django else '.*_test.py'
+    test_name_pattern = 'test.*.py' if args.django else '.*_test.py'
     for filename in args.filenames:
         base = basename(filename)
         if (
@@ -26,7 +26,7 @@ def validate_files(argv=None):
         ):
             retcode = 1
             print(
-                '{0} does not match pattern "{1}"'.format(
+                '{} does not match pattern "{}"'.format(
                     filename, test_name_pattern
                 )
             )
diff --git a/pre_commit_hooks/trailing_whitespace_fixer.py b/pre_commit_hooks/trailing_whitespace_fixer.py
index fa9b7dd..1ae15a9 100644
--- a/pre_commit_hooks/trailing_whitespace_fixer.py
+++ b/pre_commit_hooks/trailing_whitespace_fixer.py
@@ -10,10 +10,14 @@ from pre_commit_hooks.util import cmd_output
 def _fix_file(filename, is_markdown):
     with open(filename, mode='rb') as file_processed:
         lines = file_processed.readlines()
-    lines = [_process_line(line, is_markdown) for line in lines]
-    with open(filename, mode='wb') as file_processed:
-        for line in lines:
-            file_processed.write(line)
+    newlines = [_process_line(line, is_markdown) for line in lines]
+    if newlines != lines:
+        with open(filename, mode='wb') as file_processed:
+            for line in newlines:
+                file_processed.write(line)
+        return True
+    else:
+        return False
 
 
 def _process_line(line, is_markdown):
@@ -55,24 +59,26 @@ def fix_trailing_whitespace(argv=None):
         parser.error('--markdown-linebreak-ext requires a non-empty argument')
     all_markdown = '*' in md_args
     # normalize all extensions; split at ',', lowercase, and force 1 leading '.'
-    md_exts = ['.' + x.lower().lstrip('.')
-               for x in ','.join(md_args).split(',')]
+    md_exts = [
+        '.' + x.lower().lstrip('.') for x in ','.join(md_args).split(',')
+    ]
 
     # reject probable "eaten" filename as extension (skip leading '.' with [1:])
     for ext in md_exts:
         if any(c in ext[1:] for c in r'./\:'):
             parser.error(
-                "bad --markdown-linebreak-ext extension '{0}' (has . / \\ :)\n"
+                "bad --markdown-linebreak-ext extension '{}' (has . / \\ :)\n"
                 "  (probably filename; use '--markdown-linebreak-ext=EXT')"
                 .format(ext)
             )
 
     return_code = 0
     for bad_whitespace_file in bad_whitespace_files:
-        print('Fixing {0}'.format(bad_whitespace_file))
         _, extension = os.path.splitext(bad_whitespace_file.lower())
-        _fix_file(bad_whitespace_file, all_markdown or extension in md_exts)
-        return_code = 1
+        md = all_markdown or extension in md_exts
+        if _fix_file(bad_whitespace_file, md):
+            print('Fixing {}'.format(bad_whitespace_file))
+            return_code = 1
     return return_code
 
 
diff --git a/setup.py b/setup.py
index 86f3b39..3d96bda 100644
--- a/setup.py
+++ b/setup.py
@@ -6,7 +6,7 @@ setup(
     name='pre_commit_hooks',
     description='Some out-of-the-box hooks for pre-commit.',
     url='https://github.com/pre-commit/pre-commit-hooks',
-    version='0.6.1',
+    version='0.7.1',
 
     author='Anthony Sottile',
     author_email='asottile@umich.edu',
@@ -14,11 +14,10 @@ setup(
     classifiers=[
         'License :: OSI Approved :: MIT License',
         'Programming Language :: Python :: 2',
-        'Programming Language :: Python :: 2.6',
         'Programming Language :: Python :: 2.7',
         'Programming Language :: Python :: 3',
-        'Programming Language :: Python :: 3.4',
         'Programming Language :: Python :: 3.5',
+        'Programming Language :: Python :: 3.6',
         'Programming Language :: Python :: Implementation :: CPython',
         'Programming Language :: Python :: Implementation :: PyPy',
     ],
@@ -27,7 +26,6 @@ setup(
     install_requires=[
         # quickfix to prevent pep8 conflicts
         'flake8!=2.5.3',
-        'argparse',
         'autopep8>=1.1',
         'pyyaml',
         'simplejson',
diff --git a/tests/detect_aws_credentials_test.py b/tests/detect_aws_credentials_test.py
index 9c2fda7..943a3f8 100644
--- a/tests/detect_aws_credentials_test.py
+++ b/tests/detect_aws_credentials_test.py
@@ -130,3 +130,17 @@ def test_non_existent_credentials(mock_secrets_env, mock_secrets_file, capsys):
         'and environment variables.\nPlease ensure you have the '
         'correct setting for --credentials-file\n'
     )
+
+
+@patch('pre_commit_hooks.detect_aws_credentials.get_aws_secrets_from_file')
+@patch('pre_commit_hooks.detect_aws_credentials.get_aws_secrets_from_env')
+def test_non_existent_credentials_with_allow_flag(mock_secrets_env, mock_secrets_file):
+    """Test behavior with no configured AWS secrets and flag to allow when missing."""
+    mock_secrets_env.return_value = set()
+    mock_secrets_file.return_value = set()
+    ret = main((
+        get_resource_path('aws_config_without_secrets.ini'),
+        "--credentials-file=testing/resources/credentailsfilethatdoesntexist",
+        "--allow-missing-credentials"
+    ))
+    assert ret == 0
diff --git a/tests/meta_test.py b/tests/meta_test.py
new file mode 100644
index 0000000..202b3d7
--- /dev/null
+++ b/tests/meta_test.py
@@ -0,0 +1,7 @@
+import io
+
+
+def test_hooks_yaml_same_contents():
+    legacy_contents = io.open('hooks.yaml').read()
+    contents = io.open('.pre-commit-hooks.yaml').read()
+    assert legacy_contents == contents
diff --git a/tests/readme_test.py b/tests/readme_test.py
index d479d42..4d4c972 100644
--- a/tests/readme_test.py
+++ b/tests/readme_test.py
@@ -10,4 +10,4 @@ def test_readme_contains_all_hooks():
     readme_contents = io.open('README.md').read()
     hooks = yaml.load(io.open('hooks.yaml').read())
     for hook in hooks:
-        assert '`{0}`'.format(hook['id']) in readme_contents
+        assert '`{}`'.format(hook['id']) in readme_contents
diff --git a/tests/tests_should_end_in_test_test.py b/tests/tests_should_end_in_test_test.py
index a7aaf52..dc686a5 100644
--- a/tests/tests_should_end_in_test_test.py
+++ b/tests/tests_should_end_in_test_test.py
@@ -12,7 +12,7 @@ def test_validate_files_one_fails():
 
 
 def test_validate_files_django_all_pass():
-    ret = validate_files(['--django', 'test_foo.py', 'test_bar.py', 'tests/test_baz.py'])
+    ret = validate_files(['--django', 'tests.py', 'test_foo.py', 'test_bar.py', 'tests/test_baz.py'])
     assert ret == 0
 
 
diff --git a/tests/trailing_whitespace_fixer_test.py b/tests/trailing_whitespace_fixer_test.py
index 3a72ccb..eb2a1d0 100644
--- a/tests/trailing_whitespace_fixer_test.py
+++ b/tests/trailing_whitespace_fixer_test.py
@@ -20,6 +20,22 @@ def test_fixes_trailing_whitespace(input_s, expected, tmpdir):
     assert path.read() == expected
 
 
+def test_ok_with_dos_line_endings(tmpdir):
+    filename = tmpdir.join('f')
+    filename.write_binary(b'foo\r\nbar\r\nbaz\r\n')
+    ret = fix_trailing_whitespace((filename.strpath,))
+    assert filename.read_binary() == b'foo\r\nbar\r\nbaz\r\n'
+    assert ret == 0
+
+
+def test_markdown_ok(tmpdir):
+    filename = tmpdir.join('foo.md')
+    filename.write_binary(b'foo  \n')
+    ret = fix_trailing_whitespace((filename.strpath,))
+    assert filename.read_binary() == b'foo  \n'
+    assert ret == 0
+
+
 # filename, expected input, expected output
 MD_TESTS_1 = (
     ('foo.md', 'foo  \nbar \n  ', 'foo  \nbar\n\n'),