diff -r d6aa3fa646e2 Lib/inspect.py
--- a/Lib/inspect.py	Fri Feb 21 18:30:53 2014 -0500
+++ b/Lib/inspect.py	Fri Feb 21 22:19:45 2014 -0500
@@ -32,6 +32,7 @@
               'Yury Selivanov <yselivanov@sprymix.com>')
 
 import ast
+import enum
 import importlib.machinery
 import itertools
 import linecache
@@ -2027,24 +2028,22 @@
     pass
 
 
-class _ParameterKind(int):
-    def __new__(self, *args, name):
-        obj = int.__new__(self, *args)
-        obj._name = name
-        return obj
+class _ParameterKind(enum.IntEnum):
+    POSITIONAL_ONLY = 0
+    POSITIONAL_OR_KEYWORD = 1
+    VAR_POSITIONAL = 2
+    KEYWORD_ONLY = 3
+    VAR_KEYWORD = 4
 
     def __str__(self):
-        return self._name
-
-    def __repr__(self):
-        return '<_ParameterKind: {!r}>'.format(self._name)
-
-
-_POSITIONAL_ONLY        = _ParameterKind(0, name='POSITIONAL_ONLY')
-_POSITIONAL_OR_KEYWORD  = _ParameterKind(1, name='POSITIONAL_OR_KEYWORD')
-_VAR_POSITIONAL         = _ParameterKind(2, name='VAR_POSITIONAL')
-_KEYWORD_ONLY           = _ParameterKind(3, name='KEYWORD_ONLY')
-_VAR_KEYWORD            = _ParameterKind(4, name='VAR_KEYWORD')
+        return self._name_
+
+
+_POSITIONAL_ONLY         = _ParameterKind.POSITIONAL_ONLY
+_POSITIONAL_OR_KEYWORD   = _ParameterKind.POSITIONAL_OR_KEYWORD
+_VAR_POSITIONAL          = _ParameterKind.VAR_POSITIONAL
+_KEYWORD_ONLY            = _ParameterKind.KEYWORD_ONLY
+_VAR_KEYWORD             = _ParameterKind.VAR_KEYWORD
 
 
 class Parameter:
@@ -2107,6 +2106,18 @@
 
         self._partial_kwarg = _partial_kwarg
 
+    def __reduce__(self):
+        return (type(self),
+                (self._name, self._kind),
+                {'_partial_kwarg': self._partial_kwarg,
+                 '_default': self._default,
+                 '_annotation': self._annotation})
+
+    def __setstate__(self, state):
+        self._partial_kwarg = state['_partial_kwarg']
+        self._default = state['_default']
+        self._annotation = state['_annotation']
+
     @property
     def name(self):
         return self._name
@@ -2659,6 +2670,14 @@
         '''
         return args[0]._bind(args[1:], kwargs, partial=True)
 
+    def __reduce__(self):
+        return (type(self),
+                (tuple(self._parameters.values()),),
+                {'_return_annotation': self._return_annotation})
+
+    def __setstate__(self, state):
+        self._return_annotation = state['_return_annotation']
+
     def __str__(self):
         result = []
         render_pos_only_separator = False
diff -r d6aa3fa646e2 Lib/test/test_inspect.py
--- a/Lib/test/test_inspect.py	Fri Feb 21 18:30:53 2014 -0500
+++ b/Lib/test/test_inspect.py	Fri Feb 21 22:19:45 2014 -0500
@@ -8,6 +8,7 @@
 import os
 from os.path import normcase
 import _pickle
+import pickle
 import re
 import shutil
 import sys
@@ -1654,6 +1655,12 @@
         with self.assertRaisesRegex(ValueError, 'follows default argument'):
             S((pkd, pk))
 
+    def test_signature_object_pickle(self):
+        def foo(a, *, b:1={}, **kw) -> {42:'ham'}: pass
+        sig = inspect.signature(foo)
+        sig_pickled = pickle.loads(pickle.dumps(sig))
+        self.assertEqual(sig, sig_pickled)
+
     def test_signature_immutability(self):
         def test(a):
             pass