diff --git a/.travis.yml b/.travis.yml
index 58dd54a..44ea648 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,10 +3,10 @@ dist: xenial  # required for Python >= 3.7 (travis-ci/travis-ci#9069)
 language: python
 python:
   - 2.7
-  - 3.4
   - 3.5
   - 3.6
   - 3.7
+  - 3.8
   - nightly
 install:
   - pip install pyyaml coveralls flake8 flake8-import-order doc8
diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 119917f..4e56ab6 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -1,6 +1,13 @@
 Changelog
 =========
 
+1.21.0 (2020-03-24)
+-------------------
+
+- Fix ``new-lines`` rule on Python 3 with DOS line endings
+- Fix ``quoted-strings`` rule not working for string values matching scalars
+- Add ``required: only-when-needed`` option to the ``quoted-strings`` rule
+
 1.20.0 (2019-12-26)
 -------------------
 
diff --git a/tests/rules/test_quoted_strings.py b/tests/rules/test_quoted_strings.py
index 04ee492..0fdba71 100644
--- a/tests/rules/test_quoted_strings.py
+++ b/tests/rules/test_quoted_strings.py
@@ -22,6 +22,7 @@ class QuotedTestCase(RuleTestCase):
 
     def test_disabled(self):
         conf = 'quoted-strings: disable'
+
         self.check('---\n'
                    'foo: bar\n', conf)
         self.check('---\n'
@@ -30,18 +31,23 @@ class QuotedTestCase(RuleTestCase):
                    'foo: \'bar\'\n', conf)
         self.check('---\n'
                    'bar: 123\n', conf)
+        self.check('---\n'
+                   'bar: "123"\n', conf)
 
     def test_quote_type_any(self):
         conf = 'quoted-strings: {quote-type: any}\n'
+
         self.check('---\n'
                    'boolean1: true\n'
                    'number1: 123\n'
                    'string1: foo\n'                          # fails
                    'string2: "foo"\n'
-                   'string3: \'bar\'\n'
-                   'string4: !!str genericstring\n'
-                   'string5: !!str 456\n'
-                   'string6: !!str "quotedgenericstring"\n'
+                   'string3: "true"\n'
+                   'string4: "123"\n'
+                   'string5: \'bar\'\n'
+                   'string6: !!str genericstring\n'
+                   'string7: !!str 456\n'
+                   'string8: !!str "quotedgenericstring"\n'
                    'binary: !!binary binstring\n'
                    'integer: !!int intstring\n'
                    'boolean2: !!bool boolstring\n'
@@ -55,7 +61,7 @@ class QuotedTestCase(RuleTestCase):
                    '  word 1\n'
                    '  word 2\n'
                    'multiline string 3:\n'
-                   '  word 1\n'
+                   '  word 1\n'               # fails
                    '  word 2\n'
                    'multiline string 4:\n'
                    '  "word 1\\\n'
@@ -64,20 +70,24 @@ class QuotedTestCase(RuleTestCase):
 
     def test_quote_type_single(self):
         conf = 'quoted-strings: {quote-type: single}\n'
+
         self.check('---\n'
                    'boolean1: true\n'
                    'number1: 123\n'
                    'string1: foo\n'                          # fails
                    'string2: "foo"\n'                        # fails
-                   'string3: \'bar\'\n'
-                   'string4: !!str genericstring\n'
-                   'string5: !!str 456\n'
-                   'string6: !!str "quotedgenericstring"\n'
+                   'string3: "true"\n'                       # fails
+                   'string4: "123"\n'                        # fails
+                   'string5: \'bar\'\n'
+                   'string6: !!str genericstring\n'
+                   'string7: !!str 456\n'
+                   'string8: !!str "quotedgenericstring"\n'
                    'binary: !!binary binstring\n'
                    'integer: !!int intstring\n'
                    'boolean2: !!bool boolstring\n'
                    'boolean3: !!bool "quotedboolstring"\n',
-                   conf, problem1=(4, 10), problem2=(5, 10))
+                   conf, problem1=(4, 10), problem2=(5, 10),
+                   problem3=(6, 10), problem4=(7, 10))
         self.check('---\n'
                    'multiline string 1: |\n'
                    '  line 1\n'
@@ -86,7 +96,7 @@ class QuotedTestCase(RuleTestCase):
                    '  word 1\n'
                    '  word 2\n'
                    'multiline string 3:\n'
-                   '  word 1\n'
+                   '  word 1\n'               # fails
                    '  word 2\n'
                    'multiline string 4:\n'
                    '  "word 1\\\n'
@@ -95,20 +105,162 @@ class QuotedTestCase(RuleTestCase):
 
     def test_quote_type_double(self):
         conf = 'quoted-strings: {quote-type: double}\n'
+
+        self.check('---\n'
+                   'boolean1: true\n'
+                   'number1: 123\n'
+                   'string1: foo\n'                          # fails
+                   'string2: "foo"\n'
+                   'string3: "true"\n'
+                   'string4: "123"\n'
+                   'string5: \'bar\'\n'                      # fails
+                   'string6: !!str genericstring\n'
+                   'string7: !!str 456\n'
+                   'string8: !!str "quotedgenericstring"\n'
+                   'binary: !!binary binstring\n'
+                   'integer: !!int intstring\n'
+                   'boolean2: !!bool boolstring\n'
+                   'boolean3: !!bool "quotedboolstring"\n',
+                   conf, problem1=(4, 10), problem2=(8, 10))
+        self.check('---\n'
+                   'multiline string 1: |\n'
+                   '  line 1\n'
+                   '  line 2\n'
+                   'multiline string 2: >\n'
+                   '  word 1\n'
+                   '  word 2\n'
+                   'multiline string 3:\n'
+                   '  word 1\n'               # fails
+                   '  word 2\n'
+                   'multiline string 4:\n'
+                   '  "word 1\\\n'
+                   '   word 2"\n',
+                   conf, problem1=(9, 3))
+
+    def test_disallow_redundant_quotes(self):
+        conf = 'quoted-strings: {required: only-when-needed}\n'
+
+        self.check('---\n'
+                   'boolean1: true\n'
+                   'number1: 123\n'
+                   'string1: foo\n'
+                   'string2: "foo"\n'                        # fails
+                   'string3: "true"\n'
+                   'string4: "123"\n'
+                   'string5: \'bar\'\n'                      # fails
+                   'string6: !!str genericstring\n'
+                   'string7: !!str 456\n'
+                   'string8: !!str "quotedgenericstring"\n'
+                   'binary: !!binary binstring\n'
+                   'integer: !!int intstring\n'
+                   'boolean2: !!bool boolstring\n'
+                   'boolean3: !!bool "quotedboolstring"\n',
+                   conf, problem1=(5, 10), problem2=(8, 10))
+        self.check('---\n'
+                   'multiline string 1: |\n'
+                   '  line 1\n'
+                   '  line 2\n'
+                   'multiline string 2: >\n'
+                   '  word 1\n'
+                   '  word 2\n'
+                   'multiline string 3:\n'
+                   '  word 1\n'
+                   '  word 2\n'
+                   'multiline string 4:\n'
+                   '  "word 1\\\n'            # fails
+                   '   word 2"\n',
+                   conf, problem1=(12, 3))
+
+    def test_disallow_redundant_single_quotes(self):
+        conf = 'quoted-strings: {quote-type: single, ' + \
+                                'required: only-when-needed}\n'
+
+        self.check('---\n'
+                   'boolean1: true\n'
+                   'number1: 123\n'
+                   'string1: foo\n'
+                   'string2: "foo"\n'                        # fails
+                   'string3: "true"\n'                       # fails
+                   'string4: "123"\n'                        # fails
+                   'string5: \'bar\'\n'                      # fails
+                   'string6: !!str genericstring\n'
+                   'string7: !!str 456\n'
+                   'string8: !!str "quotedgenericstring"\n'
+                   'binary: !!binary binstring\n'
+                   'integer: !!int intstring\n'
+                   'boolean2: !!bool boolstring\n'
+                   'boolean3: !!bool "quotedboolstring"\n',
+                   conf, problem1=(5, 10), problem2=(6, 10),
+                   problem3=(7, 10), problem4=(8, 10))
+        self.check('---\n'
+                   'multiline string 1: |\n'
+                   '  line 1\n'
+                   '  line 2\n'
+                   'multiline string 2: >\n'
+                   '  word 1\n'
+                   '  word 2\n'
+                   'multiline string 3:\n'
+                   '  word 1\n'
+                   '  word 2\n'
+                   'multiline string 4:\n'
+                   '  "word 1\\\n'            # fails
+                   '   word 2"\n',
+                   conf, problem1=(12, 3))
+
+    def test_single_quotes_required(self):
+        conf = 'quoted-strings: {quote-type: single, required: true}\n'
+
         self.check('---\n'
                    'boolean1: true\n'
                    'number1: 123\n'
                    'string1: foo\n'                          # fails
+                   'string2: "foo"\n'                        # fails
+                   'string3: "true"\n'                       # fails
+                   'string4: "123"\n'                        # fails
+                   'string5: \'bar\'\n'
+                   'string6: !!str genericstring\n'
+                   'string7: !!str 456\n'
+                   'string8: !!str "quotedgenericstring"\n'
+                   'binary: !!binary binstring\n'
+                   'integer: !!int intstring\n'
+                   'boolean2: !!bool boolstring\n'
+                   'boolean3: !!bool "quotedboolstring"\n',
+                   conf, problem1=(4, 10), problem2=(5, 10),
+                   problem3=(6, 10), problem4=(7, 10))
+        self.check('---\n'
+                   'multiline string 1: |\n'
+                   '  line 1\n'
+                   '  line 2\n'
+                   'multiline string 2: >\n'
+                   '  word 1\n'
+                   '  word 2\n'
+                   'multiline string 3:\n'
+                   '  word 1\n'               # fails
+                   '  word 2\n'
+                   'multiline string 4:\n'
+                   '  "word 1\\\n'            # fails
+                   '   word 2"\n',
+                   conf, problem1=(9, 3), problem2=(12, 3))
+
+    def test_any_quotes_relaxed(self):
+        conf = 'quoted-strings: {quote-type: any, required: false}\n'
+
+        self.check('---\n'
+                   'boolean1: true\n'
+                   'number1: 123\n'
+                   'string1: foo\n'
                    'string2: "foo"\n'
-                   'string3: \'bar\'\n'                      # fails
-                   'string4: !!str genericstring\n'
-                   'string5: !!str 456\n'
-                   'string6: !!str "quotedgenericstring"\n'
+                   'string3: "true"\n'
+                   'string4: "123"\n'
+                   'string5: \'bar\'\n'
+                   'string6: !!str genericstring\n'
+                   'string7: !!str 456\n'
+                   'string8: !!str "quotedgenericstring"\n'
                    'binary: !!binary binstring\n'
                    'integer: !!int intstring\n'
                    'boolean2: !!bool boolstring\n'
                    'boolean3: !!bool "quotedboolstring"\n',
-                   conf, problem1=(4, 10), problem2=(6, 10))
+                   conf)
         self.check('---\n'
                    'multiline string 1: |\n'
                    '  line 1\n'
@@ -122,4 +274,73 @@ class QuotedTestCase(RuleTestCase):
                    'multiline string 4:\n'
                    '  "word 1\\\n'
                    '   word 2"\n',
+                   conf)
+
+    def test_single_quotes_relaxed(self):
+        conf = 'quoted-strings: {quote-type: single, required: false}\n'
+
+        self.check('---\n'
+                   'boolean1: true\n'
+                   'number1: 123\n'
+                   'string1: foo\n'
+                   'string2: "foo"\n'                        # fails
+                   'string3: "true"\n'                       # fails
+                   'string4: "123"\n'                        # fails
+                   'string5: \'bar\'\n'
+                   'string6: !!str genericstring\n'
+                   'string7: !!str 456\n'
+                   'string8: !!str "quotedgenericstring"\n'
+                   'binary: !!binary binstring\n'
+                   'integer: !!int intstring\n'
+                   'boolean2: !!bool boolstring\n'
+                   'boolean3: !!bool "quotedboolstring"\n',
+                   conf, problem2=(5, 10),
+                   problem3=(6, 10), problem4=(7, 10))
+        self.check('---\n'
+                   'multiline string 1: |\n'
+                   '  line 1\n'
+                   '  line 2\n'
+                   'multiline string 2: >\n'
+                   '  word 1\n'
+                   '  word 2\n'
+                   'multiline string 3:\n'
+                   '  word 1\n'
+                   '  word 2\n'
+                   'multiline string 4:\n'
+                   '  "word 1\\\n'            # fails
+                   '   word 2"\n',
+                   conf, problem1=(12, 3))
+
+    def test_quotes_required(self):
+        conf = 'quoted-strings: {quote-type: any, required: true}\n'
+
+        self.check('---\n'
+                   'boolean1: true\n'
+                   'number1: 123\n'
+                   'string1: foo\n'                          # fails
+                   'string2: "foo"\n'
+                   'string3: "true"\n'
+                   'string4: "123"\n'
+                   'string5: \'bar\'\n'
+                   'string6: !!str genericstring\n'
+                   'string7: !!str 456\n'
+                   'string8: !!str "quotedgenericstring"\n'
+                   'binary: !!binary binstring\n'
+                   'integer: !!int intstring\n'
+                   'boolean2: !!bool boolstring\n'
+                   'boolean3: !!bool "quotedboolstring"\n',
+                   conf, problem2=(4, 10))
+        self.check('---\n'
+                   'multiline string 1: |\n'
+                   '  line 1\n'
+                   '  line 2\n'
+                   'multiline string 2: >\n'
+                   '  word 1\n'
+                   '  word 2\n'
+                   'multiline string 3:\n'
+                   '  word 1\n'               # fails
+                   '  word 2\n'
+                   'multiline string 4:\n'
+                   '  "word 1\\\n'
+                   '   word 2"\n',
                    conf, problem1=(9, 3))
diff --git a/tests/test_cli.py b/tests/test_cli.py
index 4244dc8..517bc62 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -32,6 +32,29 @@ from yamllint import cli
 from yamllint import config
 
 
+class RunContext(object):
+    """Context manager for ``cli.run()`` to capture exit code and streams."""
+
+    def __init__(self, case):
+        self.stdout = self.stderr = None
+        self._raises_ctx = case.assertRaises(SystemExit)
+
+    def __enter__(self):
+        self._raises_ctx.__enter__()
+        sys.stdout = self.outstream = StringIO()
+        sys.stderr = self.errstream = StringIO()
+        return self
+
+    def __exit__(self, *exc_info):
+        self.stdout, sys.stdout = self.outstream.getvalue(), sys.__stdout__
+        self.stderr, sys.stderr = self.errstream.getvalue(), sys.__stderr__
+        return self._raises_ctx.__exit__(*exc_info)
+
+    @property
+    def returncode(self):
+        return self._raises_ctx.exception.code
+
+
 class CommandLineTestCase(unittest.TestCase):
     @classmethod
     def setUpClass(cls):
@@ -59,12 +82,15 @@ class CommandLineTestCase(unittest.TestCase):
             'no-yaml.json': '---\n'
                             'key: value\n',
             # non-ASCII chars
-            'non-ascii/utf-8': (
+            'non-ascii/éçäγλνπ¥/utf-8': (
                 u'---\n'
                 u'- hétérogénéité\n'
                 u'# 19.99 €\n'
                 u'- お早う御座います。\n'
                 u'# الأَبْجَدِيَّة العَرَبِيَّة\n').encode('utf-8'),
+            # dos line endings yaml
+            'dos.yml': '---\r\n'
+                       'dos: true',
         })
 
     @classmethod
@@ -78,6 +104,7 @@ class CommandLineTestCase(unittest.TestCase):
         self.assertEqual(
             sorted(cli.find_files_recursively([self.wd], conf)),
             [os.path.join(self.wd, 'a.yaml'),
+             os.path.join(self.wd, 'dos.yml'),
              os.path.join(self.wd, 'empty.yml'),
              os.path.join(self.wd, 's/s/s/s/s/s/s/s/s/s/s/s/s/s/s/file.yaml'),
              os.path.join(self.wd, 'sub/ok.yaml'),
@@ -123,7 +150,8 @@ class CommandLineTestCase(unittest.TestCase):
                                      '  - \'*.yml\'\n')
         self.assertEqual(
             sorted(cli.find_files_recursively([self.wd], conf)),
-            [os.path.join(self.wd, 'empty.yml')]
+            [os.path.join(self.wd, 'dos.yml'),
+             os.path.join(self.wd, 'empty.yml')]
         )
 
         conf = config.YamlLintConfig('extends: default\n'
@@ -140,9 +168,10 @@ class CommandLineTestCase(unittest.TestCase):
         self.assertEqual(
             sorted(cli.find_files_recursively([self.wd], conf)),
             [os.path.join(self.wd, 'a.yaml'),
+             os.path.join(self.wd, 'dos.yml'),
              os.path.join(self.wd, 'empty.yml'),
              os.path.join(self.wd, 'no-yaml.json'),
-             os.path.join(self.wd, 'non-ascii/utf-8'),
+             os.path.join(self.wd, 'non-ascii/éçäγλνπ¥/utf-8'),
              os.path.join(self.wd, 's/s/s/s/s/s/s/s/s/s/s/s/s/s/s/file.yaml'),
              os.path.join(self.wd, 'sub/ok.yaml'),
              os.path.join(self.wd, 'warn.yaml')]
@@ -156,9 +185,10 @@ class CommandLineTestCase(unittest.TestCase):
         self.assertEqual(
             sorted(cli.find_files_recursively([self.wd], conf)),
             [os.path.join(self.wd, 'a.yaml'),
+             os.path.join(self.wd, 'dos.yml'),
              os.path.join(self.wd, 'empty.yml'),
              os.path.join(self.wd, 'no-yaml.json'),
-             os.path.join(self.wd, 'non-ascii/utf-8'),
+             os.path.join(self.wd, 'non-ascii/éçäγλνπ¥/utf-8'),
              os.path.join(self.wd, 's/s/s/s/s/s/s/s/s/s/s/s/s/s/s/file.yaml'),
              os.path.join(self.wd, 'sub/ok.yaml'),
              os.path.join(self.wd, 'warn.yaml')]
@@ -170,205 +200,148 @@ class CommandLineTestCase(unittest.TestCase):
                                      '  - \'**/utf-8\'\n')
         self.assertEqual(
             sorted(cli.find_files_recursively([self.wd], conf)),
-            [os.path.join(self.wd, 'non-ascii/utf-8')]
+            [os.path.join(self.wd, 'non-ascii/éçäγλνπ¥/utf-8')]
         )
 
     def test_run_with_bad_arguments(self):
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
+        with RunContext(self) as ctx:
             cli.run(())
+        self.assertNotEqual(ctx.returncode, 0)
+        self.assertEqual(ctx.stdout, '')
+        self.assertRegexpMatches(ctx.stderr, r'^usage')
 
-        self.assertNotEqual(ctx.exception.code, 0)
-
-        out, err = sys.stdout.getvalue(), sys.stderr.getvalue()
-        self.assertEqual(out, '')
-        self.assertRegexpMatches(err, r'^usage')
-
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
+        with RunContext(self) as ctx:
             cli.run(('--unknown-arg', ))
+        self.assertNotEqual(ctx.returncode, 0)
+        self.assertEqual(ctx.stdout, '')
+        self.assertRegexpMatches(ctx.stderr, r'^usage')
 
-        self.assertNotEqual(ctx.exception.code, 0)
-
-        out, err = sys.stdout.getvalue(), sys.stderr.getvalue()
-        self.assertEqual(out, '')
-        self.assertRegexpMatches(err, r'^usage')
-
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
+        with RunContext(self) as ctx:
             cli.run(('-c', './conf.yaml', '-d', 'relaxed', 'file'))
-
-        self.assertNotEqual(ctx.exception.code, 0)
-
-        out, err = sys.stdout.getvalue(), sys.stderr.getvalue()
-        self.assertEqual(out, '')
+        self.assertNotEqual(ctx.returncode, 0)
+        self.assertEqual(ctx.stdout, '')
         self.assertRegexpMatches(
-            err.splitlines()[-1],
+            ctx.stderr.splitlines()[-1],
             r'^yamllint: error: argument -d\/--config-data: '
             r'not allowed with argument -c\/--config-file$'
         )
 
         # checks if reading from stdin and files are mutually exclusive
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
+        with RunContext(self) as ctx:
             cli.run(('-', 'file'))
-
-        self.assertNotEqual(ctx.exception.code, 0)
-
-        out, err = sys.stdout.getvalue(), sys.stderr.getvalue()
-        self.assertEqual(out, '')
-        self.assertRegexpMatches(err, r'^usage')
+        self.assertNotEqual(ctx.returncode, 0)
+        self.assertEqual(ctx.stdout, '')
+        self.assertRegexpMatches(ctx.stderr, r'^usage')
 
     def test_run_with_bad_config(self):
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
+        with RunContext(self) as ctx:
             cli.run(('-d', 'rules: {a: b}', 'file'))
-
-        self.assertEqual(ctx.exception.code, -1)
-
-        out, err = sys.stdout.getvalue(), sys.stderr.getvalue()
-        self.assertEqual(out, '')
-        self.assertRegexpMatches(err, r'^invalid config: no such rule')
+        self.assertEqual(ctx.returncode, -1)
+        self.assertEqual(ctx.stdout, '')
+        self.assertRegexpMatches(ctx.stderr, r'^invalid config: no such rule')
 
     def test_run_with_empty_config(self):
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
+        with RunContext(self) as ctx:
             cli.run(('-d', '', 'file'))
-
-        self.assertEqual(ctx.exception.code, -1)
-
-        out, err = sys.stdout.getvalue(), sys.stderr.getvalue()
-        self.assertEqual(out, '')
-        self.assertRegexpMatches(err, r'^invalid config: not a dict')
+        self.assertEqual(ctx.returncode, -1)
+        self.assertEqual(ctx.stdout, '')
+        self.assertRegexpMatches(ctx.stderr, r'^invalid config: not a dict')
 
     def test_run_with_config_file(self):
         with open(os.path.join(self.wd, 'config'), 'w') as f:
             f.write('rules: {trailing-spaces: disable}')
 
-        with self.assertRaises(SystemExit) as ctx:
+        with RunContext(self) as ctx:
             cli.run(('-c', f.name, os.path.join(self.wd, 'a.yaml')))
-        self.assertEqual(ctx.exception.code, 0)
+        self.assertEqual(ctx.returncode, 0)
 
         with open(os.path.join(self.wd, 'config'), 'w') as f:
             f.write('rules: {trailing-spaces: enable}')
 
-        with self.assertRaises(SystemExit) as ctx:
+        with RunContext(self) as ctx:
             cli.run(('-c', f.name, os.path.join(self.wd, 'a.yaml')))
-        self.assertEqual(ctx.exception.code, 1)
+        self.assertEqual(ctx.returncode, 1)
 
     def test_run_with_user_global_config_file(self):
         home = os.path.join(self.wd, 'fake-home')
-        os.mkdir(home)
-        dir = os.path.join(home, '.config')
-        os.mkdir(dir)
-        dir = os.path.join(dir, 'yamllint')
-        os.mkdir(dir)
+        dir = os.path.join(home, '.config', 'yamllint')
+        os.makedirs(dir)
         config = os.path.join(dir, 'config')
 
-        temp = os.environ['HOME']
+        self.addCleanup(os.environ.update, HOME=os.environ['HOME'])
         os.environ['HOME'] = home
 
         with open(config, 'w') as f:
             f.write('rules: {trailing-spaces: disable}')
 
-        with self.assertRaises(SystemExit) as ctx:
+        with RunContext(self) as ctx:
             cli.run((os.path.join(self.wd, 'a.yaml'), ))
-        self.assertEqual(ctx.exception.code, 0)
+        self.assertEqual(ctx.returncode, 0)
 
         with open(config, 'w') as f:
             f.write('rules: {trailing-spaces: enable}')
 
-        with self.assertRaises(SystemExit) as ctx:
+        with RunContext(self) as ctx:
             cli.run((os.path.join(self.wd, 'a.yaml'), ))
-        self.assertEqual(ctx.exception.code, 1)
-
-        os.environ['HOME'] = temp
+        self.assertEqual(ctx.returncode, 1)
 
     def test_run_version(self):
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
+        with RunContext(self) as ctx:
             cli.run(('--version', ))
-
-        self.assertEqual(ctx.exception.code, 0)
-
-        out, err = sys.stdout.getvalue(), sys.stderr.getvalue()
-        self.assertRegexpMatches(out + err, r'yamllint \d+\.\d+')
+        self.assertEqual(ctx.returncode, 0)
+        self.assertRegexpMatches(ctx.stdout + ctx.stderr, r'yamllint \d+\.\d+')
 
     def test_run_non_existing_file(self):
-        file = os.path.join(self.wd, 'i-do-not-exist.yaml')
-
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
-            cli.run(('-f', 'parsable', file))
+        path = os.path.join(self.wd, 'i-do-not-exist.yaml')
 
-        self.assertEqual(ctx.exception.code, -1)
-
-        out, err = sys.stdout.getvalue(), sys.stderr.getvalue()
-        self.assertEqual(out, '')
-        self.assertRegexpMatches(err, r'No such file or directory')
+        with RunContext(self) as ctx:
+            cli.run(('-f', 'parsable', path))
+        self.assertEqual(ctx.returncode, -1)
+        self.assertEqual(ctx.stdout, '')
+        self.assertRegexpMatches(ctx.stderr, r'No such file or directory')
 
     def test_run_one_problem_file(self):
-        file = os.path.join(self.wd, 'a.yaml')
-
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
-            cli.run(('-f', 'parsable', file))
+        path = os.path.join(self.wd, 'a.yaml')
 
-        self.assertEqual(ctx.exception.code, 1)
-
-        out, err = sys.stdout.getvalue(), sys.stderr.getvalue()
-        self.assertEqual(out, (
+        with RunContext(self) as ctx:
+            cli.run(('-f', 'parsable', path))
+        self.assertEqual(ctx.returncode, 1)
+        self.assertEqual(ctx.stdout, (
             '%s:2:4: [error] trailing spaces (trailing-spaces)\n'
             '%s:3:4: [error] no new line character at the end of file '
-            '(new-line-at-end-of-file)\n') % (file, file))
-        self.assertEqual(err, '')
+            '(new-line-at-end-of-file)\n' % (path, path)))
+        self.assertEqual(ctx.stderr, '')
 
     def test_run_one_warning(self):
-        file = os.path.join(self.wd, 'warn.yaml')
+        path = os.path.join(self.wd, 'warn.yaml')
 
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
-            cli.run(('-f', 'parsable', file))
-
-        self.assertEqual(ctx.exception.code, 0)
+        with RunContext(self) as ctx:
+            cli.run(('-f', 'parsable', path))
+        self.assertEqual(ctx.returncode, 0)
 
     def test_run_warning_in_strict_mode(self):
-        file = os.path.join(self.wd, 'warn.yaml')
-
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
-            cli.run(('-f', 'parsable', '--strict', file))
+        path = os.path.join(self.wd, 'warn.yaml')
 
-        self.assertEqual(ctx.exception.code, 2)
+        with RunContext(self) as ctx:
+            cli.run(('-f', 'parsable', '--strict', path))
+        self.assertEqual(ctx.returncode, 2)
 
     def test_run_one_ok_file(self):
-        file = os.path.join(self.wd, 'sub', 'ok.yaml')
-
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
-            cli.run(('-f', 'parsable', file))
+        path = os.path.join(self.wd, 'sub', 'ok.yaml')
 
-        self.assertEqual(ctx.exception.code, 0)
-
-        out, err = sys.stdout.getvalue(), sys.stderr.getvalue()
-        self.assertEqual(out, '')
-        self.assertEqual(err, '')
+        with RunContext(self) as ctx:
+            cli.run(('-f', 'parsable', path))
+        self.assertEqual((ctx.returncode, ctx.stdout, ctx.stderr), (0, '', ''))
 
     def test_run_empty_file(self):
-        file = os.path.join(self.wd, 'empty.yml')
-
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
-            cli.run(('-f', 'parsable', file))
+        path = os.path.join(self.wd, 'empty.yml')
 
-        self.assertEqual(ctx.exception.code, 0)
-
-        out, err = sys.stdout.getvalue(), sys.stderr.getvalue()
-        self.assertEqual(out, '')
-        self.assertEqual(err, '')
+        with RunContext(self) as ctx:
+            cli.run(('-f', 'parsable', path))
+        self.assertEqual((ctx.returncode, ctx.stdout, ctx.stderr), (0, '', ''))
 
     def test_run_non_ascii_file(self):
-        file = os.path.join(self.wd, 'non-ascii', 'utf-8')
+        path = os.path.join(self.wd, 'non-ascii', 'éçäγλνπ¥', 'utf-8')
 
         # Make sure the default localization conditions on this "system"
         # support UTF-8 encoding.
@@ -377,63 +350,46 @@ class CommandLineTestCase(unittest.TestCase):
             locale.setlocale(locale.LC_ALL, 'C.UTF-8')
         except locale.Error:
             locale.setlocale(locale.LC_ALL, 'en_US.UTF-8')
+        self.addCleanup(locale.setlocale, locale.LC_ALL, loc)
 
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
-            cli.run(('-f', 'parsable', file))
-
-        locale.setlocale(locale.LC_ALL, loc)
-
-        self.assertEqual(ctx.exception.code, 0)
-
-        out, err = sys.stdout.getvalue(), sys.stderr.getvalue()
-        self.assertEqual(out, '')
-        self.assertEqual(err, '')
+        with RunContext(self) as ctx:
+            cli.run(('-f', 'parsable', path))
+        self.assertEqual((ctx.returncode, ctx.stdout, ctx.stderr), (0, '', ''))
 
     def test_run_multiple_files(self):
         items = [os.path.join(self.wd, 'empty.yml'),
                  os.path.join(self.wd, 's')]
-        file = items[1] + '/s/s/s/s/s/s/s/s/s/s/s/s/s/s/file.yaml'
+        path = items[1] + '/s/s/s/s/s/s/s/s/s/s/s/s/s/s/file.yaml'
 
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
+        with RunContext(self) as ctx:
             cli.run(['-f', 'parsable'] + items)
-
-        self.assertEqual(ctx.exception.code, 1)
-
-        out, err = sys.stdout.getvalue(), sys.stderr.getvalue()
-        self.assertEqual(out, (
+        self.assertEqual((ctx.returncode, ctx.stderr), (1, ''))
+        self.assertEqual(ctx.stdout, (
             '%s:3:1: [error] duplication of key "key" in mapping '
-            '(key-duplicates)\n') % file)
-        self.assertEqual(err, '')
+            '(key-duplicates)\n') % path)
 
     def test_run_piped_output_nocolor(self):
-        file = os.path.join(self.wd, 'a.yaml')
-
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
-            cli.run((file, ))
-
-        self.assertEqual(ctx.exception.code, 1)
+        path = os.path.join(self.wd, 'a.yaml')
 
-        out, err = sys.stdout.getvalue(), sys.stderr.getvalue()
-        self.assertEqual(out, (
+        with RunContext(self) as ctx:
+            cli.run((path, ))
+        self.assertEqual((ctx.returncode, ctx.stderr), (1, ''))
+        self.assertEqual(ctx.stdout, (
             '%s\n'
             '  2:4       error    trailing spaces  (trailing-spaces)\n'
             '  3:4       error    no new line character at the end of file  '
             '(new-line-at-end-of-file)\n'
-            '\n' % file))
-        self.assertEqual(err, '')
+            '\n' % path))
 
     def test_run_default_format_output_in_tty(self):
-        file = os.path.join(self.wd, 'a.yaml')
+        path = os.path.join(self.wd, 'a.yaml')
 
         # Create a pseudo-TTY and redirect stdout to it
         master, slave = pty.openpty()
         sys.stdout = sys.stderr = os.fdopen(slave, 'w')
 
         with self.assertRaises(SystemExit) as ctx:
-            cli.run((file, ))
+            cli.run((path, ))
         sys.stdout.flush()
 
         self.assertEqual(ctx.exception.code, 1)
@@ -456,114 +412,108 @@ class CommandLineTestCase(unittest.TestCase):
             '  \033[2m3:4\033[0m       \033[31merror\033[0m    '
             'no new line character at the end of file  '
             '\033[2m(new-line-at-end-of-file)\033[0m\n'
-            '\n' % file))
+            '\n' % path))
 
     def test_run_default_format_output_without_tty(self):
-        file = os.path.join(self.wd, 'a.yaml')
-
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
-            cli.run((file, ))
+        path = os.path.join(self.wd, 'a.yaml')
 
-        self.assertEqual(ctx.exception.code, 1)
-
-        out, err = sys.stdout.getvalue(), sys.stderr.getvalue()
-        self.assertEqual(out, (
+        with RunContext(self) as ctx:
+            cli.run((path, ))
+        expected_out = (
             '%s\n'
             '  2:4       error    trailing spaces  (trailing-spaces)\n'
             '  3:4       error    no new line character at the end of file  '
             '(new-line-at-end-of-file)\n'
-            '\n' % file))
-        self.assertEqual(err, '')
+            '\n' % path)
+        self.assertEqual(
+            (ctx.returncode, ctx.stdout, ctx.stderr), (1, expected_out, ''))
 
     def test_run_auto_output_without_tty_output(self):
-        file = os.path.join(self.wd, 'a.yaml')
-
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
-            cli.run((file, '--format', 'auto'))
+        path = os.path.join(self.wd, 'a.yaml')
 
-        self.assertEqual(ctx.exception.code, 1)
-
-        out, err = sys.stdout.getvalue(), sys.stderr.getvalue()
-        self.assertEqual(out, (
+        with RunContext(self) as ctx:
+            cli.run((path, '--format', 'auto'))
+        expected_out = (
             '%s\n'
             '  2:4       error    trailing spaces  (trailing-spaces)\n'
             '  3:4       error    no new line character at the end of file  '
             '(new-line-at-end-of-file)\n'
-            '\n' % file))
-        self.assertEqual(err, '')
+            '\n' % path)
+        self.assertEqual(
+            (ctx.returncode, ctx.stdout, ctx.stderr), (1, expected_out, ''))
 
     def test_run_format_colored(self):
-        file = os.path.join(self.wd, 'a.yaml')
-
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
-            cli.run((file, '--format', 'colored'))
+        path = os.path.join(self.wd, 'a.yaml')
 
-        self.assertEqual(ctx.exception.code, 1)
-
-        out, err = sys.stdout.getvalue(), sys.stderr.getvalue()
-        self.assertEqual(out, (
+        with RunContext(self) as ctx:
+            cli.run((path, '--format', 'colored'))
+        expected_out = (
             '\033[4m%s\033[0m\n'
             '  \033[2m2:4\033[0m       \033[31merror\033[0m    '
             'trailing spaces  \033[2m(trailing-spaces)\033[0m\n'
             '  \033[2m3:4\033[0m       \033[31merror\033[0m    '
             'no new line character at the end of file  '
             '\033[2m(new-line-at-end-of-file)\033[0m\n'
-            '\n' % file))
-        self.assertEqual(err, '')
+            '\n' % path)
+        self.assertEqual(
+            (ctx.returncode, ctx.stdout, ctx.stderr), (1, expected_out, ''))
 
     def test_run_read_from_stdin(self):
         # prepares stdin with an invalid yaml string so that we can check
         # for its specific error, and be assured that stdin was read
-        sys.stdout, sys.stderr = StringIO(), StringIO()
+        self.addCleanup(setattr, sys, 'stdin', sys.__stdin__)
         sys.stdin = StringIO(
             'I am a string\n'
             'therefore: I am an error\n')
 
-        with self.assertRaises(SystemExit) as ctx:
+        with RunContext(self) as ctx:
             cli.run(('-', '-f', 'parsable'))
-
-        self.assertNotEqual(ctx.exception.code, 0)
-
-        out, err = sys.stdout.getvalue(), sys.stderr.getvalue()
-        self.assertEqual(out, (
+        expected_out = (
             'stdin:2:10: [error] syntax error: '
-            'mapping values are not allowed here (syntax)\n'))
-        self.assertEqual(err, '')
+            'mapping values are not allowed here (syntax)\n')
+        self.assertEqual(
+            (ctx.returncode, ctx.stdout, ctx.stderr), (1, expected_out, ''))
 
     def test_run_no_warnings(self):
-        file = os.path.join(self.wd, 'a.yaml')
+        path = os.path.join(self.wd, 'a.yaml')
 
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
-            cli.run((file, '--no-warnings', '-f', 'auto'))
-
-        self.assertEqual(ctx.exception.code, 1)
-
-        out, err = sys.stdout.getvalue(), sys.stderr.getvalue()
-        self.assertEqual(out, (
+        with RunContext(self) as ctx:
+            cli.run((path, '--no-warnings', '-f', 'auto'))
+        expected_out = (
             '%s\n'
             '  2:4       error    trailing spaces  (trailing-spaces)\n'
             '  3:4       error    no new line character at the end of file  '
             '(new-line-at-end-of-file)\n'
-            '\n' % file))
-        self.assertEqual(err, '')
-
-        file = os.path.join(self.wd, 'warn.yaml')
+            '\n' % path)
+        self.assertEqual(
+            (ctx.returncode, ctx.stdout, ctx.stderr), (1, expected_out, ''))
 
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
-            cli.run((file, '--no-warnings', '-f', 'auto'))
+        path = os.path.join(self.wd, 'warn.yaml')
 
-        self.assertEqual(ctx.exception.code, 0)
+        with RunContext(self) as ctx:
+            cli.run((path, '--no-warnings', '-f', 'auto'))
+        self.assertEqual(ctx.returncode, 0)
 
     def test_run_no_warnings_and_strict(self):
-        file = os.path.join(self.wd, 'warn.yaml')
+        path = os.path.join(self.wd, 'warn.yaml')
 
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        with self.assertRaises(SystemExit) as ctx:
-            cli.run((file, '--no-warnings', '-s'))
+        with RunContext(self) as ctx:
+            cli.run((path, '--no-warnings', '-s'))
+        self.assertEqual(ctx.returncode, 2)
+
+    def test_run_non_universal_newline(self):
+        path = os.path.join(self.wd, 'dos.yml')
 
-        self.assertEqual(ctx.exception.code, 2)
+        with RunContext(self) as ctx:
+            cli.run(('-d', 'rules:\n  new-lines:\n    type: dos', path))
+        self.assertEqual((ctx.returncode, ctx.stdout, ctx.stderr), (0, '', ''))
+
+        with RunContext(self) as ctx:
+            cli.run(('-d', 'rules:\n  new-lines:\n    type: unix', path))
+        expected_out = (
+            '%s\n'
+            '  1:4       error    wrong new line character: expected \\n'
+            '  (new-lines)\n'
+            '\n' % path)
+        self.assertEqual(
+            (ctx.returncode, ctx.stdout, ctx.stderr), (1, expected_out, ''))
diff --git a/yamllint/__init__.py b/yamllint/__init__.py
index 676c80f..5b04ef6 100644
--- a/yamllint/__init__.py
+++ b/yamllint/__init__.py
@@ -22,7 +22,7 @@ indentation, etc."""
 
 
 APP_NAME = 'yamllint'
-APP_VERSION = '1.20.0'
+APP_VERSION = '1.21.0'
 APP_DESCRIPTION = __doc__
 
 __author__ = u'Adrien Vergé'
diff --git a/yamllint/cli.py b/yamllint/cli.py
index 26bdb1f..e99fd2c 100644
--- a/yamllint/cli.py
+++ b/yamllint/cli.py
@@ -17,6 +17,7 @@
 from __future__ import print_function
 
 import argparse
+import io
 import os
 import platform
 import sys
@@ -176,7 +177,7 @@ def run(argv=None):
     for file in find_files_recursively(args.files, conf):
         filepath = file[2:] if file.startswith('./') else file
         try:
-            with open(file) as f:
+            with io.open(file, newline='') as f:
                 problems = linter.run(f, conf, filepath)
         except EnvironmentError as e:
             print(e, file=sys.stderr)
diff --git a/yamllint/rules/quoted_strings.py b/yamllint/rules/quoted_strings.py
index b019261..aaa635d 100644
--- a/yamllint/rules/quoted_strings.py
+++ b/yamllint/rules/quoted_strings.py
@@ -15,15 +15,23 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 """
-Use this rule to forbid any string values that are not quoted.
-You can also enforce the type of the quote used using the ``quote-type`` option
-(``single``, ``double`` or ``any``).
+Use this rule to forbid any string values that are not quoted, or to prevent
+quoted strings without needing it. You can also enforce the type of the quote
+used.
+
+.. rubric:: Options
+
+* ``quote-type`` defines allowed quotes: ``single``, ``double`` or ``any``
+  (default).
+* ``required`` defines whether using quotes in string values is required
+  (``true``, default) or not (``false``), or only allowed when really needed
+  (``only-when-needed``).
 
 **Note**: Multi-line strings (with ``|`` or ``>``) will not be checked.
 
 .. rubric:: Examples
 
-#. With ``quoted-strings: {quote-type: any}``
+#. With ``quoted-strings: {quote-type: any, required: true}``
 
    the following code snippet would **PASS**:
    ::
@@ -37,6 +45,24 @@ You can also enforce the type of the quote used using the ``quote-type`` option
    ::
 
     foo: bar
+
+#. With ``quoted-strings: {quote-type: single, required: only-when-needed}``
+
+   the following code snippet would **PASS**:
+   ::
+
+    foo: bar
+    bar: foo
+    not_number: '123'
+    not_boolean: 'true'
+    not_comment: '# comment'
+    not_list: '[1, 2, 3]'
+    not_map: '{a: 1, b: 2}'
+
+   the following code snippet would **FAIL**:
+   ::
+
+    foo: 'bar'
 """
 
 import yaml
@@ -45,34 +71,76 @@ from yamllint.linter import LintProblem
 
 ID = 'quoted-strings'
 TYPE = 'token'
-CONF = {'quote-type': ('any', 'single', 'double')}
-DEFAULT = {'quote-type': 'any'}
+CONF = {'quote-type': ('any', 'single', 'double'),
+        'required': (True, False, 'only-when-needed')}
+DEFAULT = {'quote-type': 'any',
+           'required': True}
+
+DEFAULT_SCALAR_TAG = u'tag:yaml.org,2002:str'
+START_TOKENS = {'#', '*', '!', '?', '@', '`', '&',
+                ',', '-', '{', '}', '[', ']', ':'}
+
+
+def quote_match(quote_type, token_style):
+    return ((quote_type == 'any') or
+            (quote_type == 'single' and token_style == "'") or
+            (quote_type == 'double' and token_style == '"'))
 
 
 def check(conf, token, prev, next, nextnext, context):
+    if not (isinstance(token, yaml.tokens.ScalarToken) and
+            isinstance(prev, (yaml.ValueToken, yaml.TagToken))):
+        return
+
+    # Ignore explicit types, e.g. !!str testtest or !!int 42
+    if (prev and isinstance(prev, yaml.tokens.TagToken) and
+            prev.value[0] == '!!'):
+        return
+
+    # Ignore numbers, booleans, etc.
+    resolver = yaml.resolver.Resolver()
+    tag = resolver.resolve(yaml.nodes.ScalarNode, token.value, (True, False))
+    if token.plain and tag != DEFAULT_SCALAR_TAG:
+        return
+
+    # Ignore multi-line strings
+    if (not token.plain) and (token.style == "|" or token.style == ">"):
+        return
+
     quote_type = conf['quote-type']
+    required = conf['required']
 
-    if (isinstance(token, yaml.tokens.ScalarToken) and
-            isinstance(prev, (yaml.ValueToken, yaml.TagToken))):
-        # Ignore explicit types, e.g. !!str testtest or !!int 42
-        if (prev and isinstance(prev, yaml.tokens.TagToken) and
-                prev.value[0] == '!!'):
-            return
-
-        # Ignore numbers, booleans, etc.
-        resolver = yaml.resolver.Resolver()
-        if resolver.resolve(yaml.nodes.ScalarNode, token.value,
-                            (True, False)) != 'tag:yaml.org,2002:str':
-            return
-
-        # Ignore multi-line strings
-        if (not token.plain) and (token.style == "|" or token.style == ">"):
-            return
-
-        if ((quote_type == 'single' and token.style != "'") or
-                (quote_type == 'double' and token.style != '"') or
-                (quote_type == 'any' and token.style is None)):
-            yield LintProblem(
-                token.start_mark.line + 1,
-                token.start_mark.column + 1,
-                "string value is not quoted with %s quotes" % (quote_type))
+    # Completely relaxed about quotes (same as the rule being disabled)
+    if required is False and quote_type == 'any':
+        return
+
+    msg = None
+    if required is True:
+
+        # Quotes are mandatory and need to match config
+        if token.style is None or not quote_match(quote_type, token.style):
+            msg = "string value is not quoted with %s quotes" % (quote_type)
+
+    elif required is False:
+
+        # Quotes are not mandatory but when used need to match config
+        if token.style and not quote_match(quote_type, token.style):
+            msg = "string value is not quoted with %s quotes" % (quote_type)
+
+    elif not token.plain:
+
+        # Quotes are disallowed when not needed
+        if (tag == DEFAULT_SCALAR_TAG and token.value
+                and token.value[0] not in START_TOKENS):
+            msg = "string value is redundantly quoted with %s quotes" % (
+                quote_type)
+
+        # But when used need to match config
+        elif token.style and not quote_match(quote_type, token.style):
+            msg = "string value is not quoted with %s quotes" % (quote_type)
+
+    if msg is not None:
+        yield LintProblem(
+            token.start_mark.line + 1,
+            token.start_mark.column + 1,
+            msg)