diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 11526ea..1b1ad17 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -16,6 +16,8 @@ Version 0.4.1
 
 - All ``create`` arguments from all storages are gone. Vdirsyncer now asks if
   it should try to create collections.
+- The old config values ``True``, ``False``, ``on``, ``off`` and ``None`` are
+  now invalid.
 
 Version 0.4.0
 =============
diff --git a/tests/test_cli.py b/tests/test_cli.py
index b42c95f..12cc7f5 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -55,7 +55,7 @@ def test_load_config(monkeypatch):
         type = filesystem
         path = /tmp/contacts/
         fileext = .vcf
-        yesno = off
+        yesno = false
         number = 42
 
         [storage bob_b]
@@ -489,45 +489,31 @@ def test_create_collections(tmpdir, runner):
         set('abc')
 
 
-def test_parse_config_value():
-    x = cli.utils.parse_config_value
-    with pytest.raises(ValueError):
-        x('123  # comment!')
+def test_parse_config_value(capsys):
+    invalid = object()
 
-    assert x('"123  # comment!"') == '123  # comment!'
-    assert x('True') is True
-    assert x('False') is False
-    assert x('Yes') is True
-    assert x('3.14') == 3.14
-    assert x('') == ''
-    assert x('""') == ''
+    def x(s):
+        try:
+            rv = cli.utils.parse_config_value(s)
+        except ValueError:
+            return invalid
+        else:
+            warnings = capsys.readouterr()[1]
+            return rv, len(warnings.splitlines())
 
+    assert x('123  # comment!') is invalid
 
-def test_parse_options():
-    o = {
-        'foo': 'yes',
-        'hah': 'true',
-        'bar': '',
-        'baz': 'whatever',
-        'bam': '123',
-        'asd': 'off'
-    }
+    assert x('True') == ('True', 1)
+    assert x('False') == ('False', 1)
+    assert x('Yes') == ('Yes', 1)
+    assert x('None') == ('None', 1)
+    assert x('"True"') == ('True', 0)
+    assert x('"False"') == ('False', 0)
 
-    a = dict(cli.utils.parse_options(o.items()))
-
-    expected = {
-        'foo': True,
-        'hah': True,
-        'bar': '',
-        'baz': 'whatever',
-        'bam': 123,
-        'asd': False
-    }
-
-    assert a == expected
-
-    for key in a:
-        # Yes, we want a very strong typecheck here, because we actually have
-        # to differentiate between bool and int, and in Python 2, bool is a
-        # subclass of int.
-        assert a[key].__class__ is expected[key].__class__
+    assert x('"123  # comment!"') == ('123  # comment!', 0)
+    assert x('true') == (True, 0)
+    assert x('false') == (False, 0)
+    assert x('null') == (None, 0)
+    assert x('3.14') == (3.14, 0)
+    assert x('') == ('', 0)
+    assert x('""') == ('', 0)
diff --git a/vdirsyncer/cli/utils.py b/vdirsyncer/cli/utils.py
index 211e0ba..eb5720b 100644
--- a/vdirsyncer/cli/utils.py
+++ b/vdirsyncer/cli/utils.py
@@ -471,28 +471,17 @@ def parse_config_value(value):
     try:
         return json.loads(value)
     except ValueError:
-        rv = value
+        pass
 
-    if value.lower() in ('on', 'true', 'yes'):
-        cli_logger.warning(
-            '{} is deprecated for the config, please use true.\n'
-            'The old form will be removed in 0.4.0.'
-            .format(value)
-        )
-        return True
-    if value.lower() in ('off', 'false', 'no'):
-        cli_logger.warning(
-            '{} is deprecated for the config, please use false.\n'
-            'The old form will be removed in 0.4.0.'
-            .format(value)
-        )
-        return False
-    if value.lower() == 'none':
-        cli_logger.warning(
-            'None is deprecated for the config, please use null.\n'
-            'The old form will be removed in 0.4.0.'
-        )
-        return None
+    for wrong, right in [
+        (('on', 'yes'), 'true'),
+        (('off', 'no'), 'false'),
+        (('none',), 'null')
+    ]:
+        if value.lower() in wrong + (right,):
+            cli_logger.warning('You probably meant {} instead of "{}", which '
+                               'will now be interpreted as a literal string.'
+                               .format(right, value))
 
     if '#' in value:
         raise ValueError('Invalid value:{}\n'
@@ -508,7 +497,7 @@ def parse_config_value(value):
         #  # my comment
         raise ValueError('No multiline-values allowed:\n{}'.format(value))
 
-    return rv
+    return value
 
 
 def parse_options(items, section=None):