diff -r 20f18e5e8bfc Doc/library/http.cookies.rst
--- a/Doc/library/http.cookies.rst	Sat Jan 07 00:08:29 2017 +0100
+++ b/Doc/library/http.cookies.rst	Sat Jan 07 13:11:01 2017 +0200
@@ -148,39 +148,31 @@ Morsel Objects
       :meth:`~Morsel.__eq__` now takes :attr:`~Morsel.key` and :attr:`~Morsel.value`
       into account.
 
+   .. versionchanged:: 3.7
+      Attributes :attr:`~Morsel.key`, :attr:`~Morsel.value` and
+      :attr:`~Morsel.coded_value` are read-only.  Use :meth:`~Morsel.set` for
+      setting them.
+
 
 .. attribute:: Morsel.value
 
    The value of the cookie.
 
-   .. deprecated:: 3.5
-      assigning to ``value``; use :meth:`~Morsel.set` instead.
-
 
 .. attribute:: Morsel.coded_value
 
    The encoded value of the cookie --- this is what should be sent.
 
-   .. deprecated:: 3.5
-      assigning to ``coded_value``; use :meth:`~Morsel.set` instead.
-
 
 .. attribute:: Morsel.key
 
    The name of the cookie.
 
-   .. deprecated:: 3.5
-      assigning to ``key``; use :meth:`~Morsel.set` instead.
-
 
 .. method:: Morsel.set(key, value, coded_value)
 
    Set the *key*, *value* and *coded_value* attributes.
 
-   .. deprecated:: 3.5
-      The undocumented *LegalChars* parameter is ignored and will be removed in
-      a future version.
-
 
 .. method:: Morsel.isReservedKey(K)
 
diff -r 20f18e5e8bfc Lib/http/cookies.py
--- a/Lib/http/cookies.py	Sat Jan 07 00:08:29 2017 +0100
+++ b/Lib/http/cookies.py	Sat Jan 07 13:11:01 2017 +0200
@@ -138,12 +138,6 @@ import string
 _semispacejoin = '; '.join
 _spacejoin = ' '.join
 
-def _warn_deprecated_setter(setter):
-    import warnings
-    msg = ('The .%s setter is deprecated. The attribute will be read-only in '
-           'future releases. Please use the set() method instead.' % setter)
-    warnings.warn(msg, DeprecationWarning, stacklevel=3)
-
 #
 # Define an exception visible to External modules
 #
@@ -303,29 +297,14 @@ class Morsel(dict):
     def key(self):
         return self._key
 
-    @key.setter
-    def key(self, key):
-        _warn_deprecated_setter('key')
-        self._key = key
-
     @property
     def value(self):
         return self._value
 
-    @value.setter
-    def value(self, value):
-        _warn_deprecated_setter('value')
-        self._value = value
-
     @property
     def coded_value(self):
         return self._coded_value
 
-    @coded_value.setter
-    def coded_value(self, coded_value):
-        _warn_deprecated_setter('coded_value')
-        self._coded_value = coded_value
-
     def __setitem__(self, K, V):
         K = K.lower()
         if not K in self._reserved:
@@ -366,14 +345,7 @@ class Morsel(dict):
     def isReservedKey(self, K):
         return K.lower() in self._reserved
 
-    def set(self, key, val, coded_val, LegalChars=_LegalChars):
-        if LegalChars != _LegalChars:
-            import warnings
-            warnings.warn(
-                'LegalChars parameter is deprecated, ignored and will '
-                'be removed in future versions.', DeprecationWarning,
-                stacklevel=2)
-
+    def set(self, key, val, coded_val):
         if key.lower() in self._reserved:
             raise CookieError('Attempt to set a reserved key %r' % (key,))
         if not _is_legal_key(key):
diff -r 20f18e5e8bfc Lib/test/test_http_cookies.py
--- a/Lib/test/test_http_cookies.py	Sat Jan 07 00:08:29 2017 +0100
+++ b/Lib/test/test_http_cookies.py	Sat Jan 07 13:11:01 2017 +0200
@@ -12,8 +12,8 @@ class CookieTests(unittest.TestCase):
     def setUp(self):
         self._warnings_manager = check_warnings()
         self._warnings_manager.__enter__()
-        warnings.filterwarnings("ignore", ".* class is insecure.*",
-                                DeprecationWarning)
+        #warnings.filterwarnings("ignore", ".* class is insecure.*",
+                                #DeprecationWarning)
 
     def tearDown(self):
         self._warnings_manager.__exit__(None, None, None)
@@ -256,6 +256,9 @@ class MorselTests(unittest.TestCase):
             # Check output and js_output.
             M['path'] = '/foo' # Try a reserved key as well
             M.set(i, "%s_val" % i, "%s_coded_val" % i)
+            self.assertEqual(M.key, i)
+            self.assertEqual(M.value, "%s_val" % i)
+            self.assertEqual(M.coded_value, "%s_coded_val" % i)
             self.assertEqual(
                 M.output(),
                 "Set-Cookie: %s=%s; Path=/foo" % (i, "%s_coded_val" % i))
@@ -272,16 +275,14 @@ class MorselTests(unittest.TestCase):
             self.assertRaises(cookies.CookieError,
                               M.set, i, '%s_value' % i, '%s_value' % i)
 
-    def test_deprecation(self):
+    def test_set_properties(self):
         morsel = cookies.Morsel()
-        with self.assertWarnsRegex(DeprecationWarning, r'\bkey\b'):
+        with self.assertRaises(AttributeError):
             morsel.key = ''
-        with self.assertWarnsRegex(DeprecationWarning, r'\bvalue\b'):
+        with self.assertRaises(AttributeError):
             morsel.value = ''
-        with self.assertWarnsRegex(DeprecationWarning, r'\bcoded_value\b'):
+        with self.assertRaises(AttributeError):
             morsel.coded_value = ''
-        with self.assertWarnsRegex(DeprecationWarning, r'\bLegalChars\b'):
-            morsel.set('key', 'value', 'coded_value', LegalChars='.*')
 
     def test_eq(self):
         base_case = ('key', 'value', '"value"')