diff -r a175cc162933 Modules/_codecsmodule.c
--- a/Modules/_codecsmodule.c	Sat Aug 08 11:20:24 2015 -0400
+++ b/Modules/_codecsmodule.c	Sat Aug 08 11:39:32 2015 -0400
@@ -91,22 +91,23 @@
 /*[clinic input]
 _codecs.encode
     obj: object
-    encoding: str(c_default="NULL") = sys.getdefaultencoding()
+    encoding: str(accept={str, NoneType}) = NULL
     errors: str(c_default="NULL") = "strict"
 
 Encodes obj using the codec registered for encoding.
 
-encoding defaults to the default encoding.  errors may be given to set a
-different error handling scheme.  Default is 'strict' meaning that encoding
-errors raise a ValueError.  Other possible values are 'ignore', 'replace'
-and 'backslashreplace' as well as any other name registered with
-codecs.register_error that can handle ValueErrors.
+encoding defaults to the default encoding (see sys.getdefaultencoding()).
+
+errors may be given to set a different error handling scheme.  Default is
+'strict' meaning that encoding errors raise a ValueError.  Other possible
+values are 'ignore', 'replace' and 'backslashreplace' as well as any other
+name registered with codecs.register_error that can handle ValueErrors.
 [clinic start generated code]*/
 
 static PyObject *
 _codecs_encode_impl(PyModuleDef *module, PyObject *obj, const char *encoding,
                     const char *errors)
-/*[clinic end generated code: output=5c073f62249c8d7c input=2440d769df020a0e]*/
+/*[clinic end generated code: output=5c073f62249c8d7c input=b06ddc7832b3b030]*/
 {
     if (encoding == NULL)
         encoding = PyUnicode_GetDefaultEncoding();
@@ -118,22 +119,23 @@
 /*[clinic input]
 _codecs.decode
     obj: object
-    encoding: str(c_default="NULL") = sys.getdefaultencoding()
+    encoding: str(accept={str, NoneType}) = NULL
     errors: str(c_default="NULL") = "strict"
 
 Decodes obj using the codec registered for encoding.
 
-encoding defaults to the default encoding.  errors may be given to set a
-different error handling scheme.  Default is 'strict' meaning that encoding
-errors raise a ValueError.  Other possible values are 'ignore', 'replace'
-and 'backslashreplace' as well as any other name registered with
-codecs.register_error that can handle ValueErrors.
+encoding defaults to the default encoding (see sys.getdefaultencoding()).
+
+errors may be given to set a different error handling scheme.  Default is
+'strict' meaning that encoding errors raise a ValueError.  Other possible
+values are 'ignore', 'replace' and 'backslashreplace' as well as any other
+name registered with codecs.register_error that can handle ValueErrors.
 [clinic start generated code]*/
 
 static PyObject *
 _codecs_decode_impl(PyModuleDef *module, PyObject *obj, const char *encoding,
                     const char *errors)
-/*[clinic end generated code: output=c81cbf6189a7f878 input=a351e5f5baad1544]*/
+/*[clinic end generated code: output=c81cbf6189a7f878 input=af59bf6e965bca8b]*/
 {
     if (encoding == NULL)
         encoding = PyUnicode_GetDefaultEncoding();
diff -r a175cc162933 Modules/clinic/_codecsmodule.c.h
--- a/Modules/clinic/_codecsmodule.c.h	Sat Aug 08 11:20:24 2015 -0400
+++ b/Modules/clinic/_codecsmodule.c.h	Sat Aug 08 11:39:32 2015 -0400
@@ -42,17 +42,17 @@
 }
 
 PyDoc_STRVAR(_codecs_encode__doc__,
-"encode($module, /, obj, encoding=sys.getdefaultencoding(),\n"
-"       errors=\'strict\')\n"
+"encode($module, /, obj, encoding=None, errors=\'strict\')\n"
 "--\n"
 "\n"
 "Encodes obj using the codec registered for encoding.\n"
 "\n"
-"encoding defaults to the default encoding.  errors may be given to set a\n"
-"different error handling scheme.  Default is \'strict\' meaning that encoding\n"
-"errors raise a ValueError.  Other possible values are \'ignore\', \'replace\'\n"
-"and \'backslashreplace\' as well as any other name registered with\n"
-"codecs.register_error that can handle ValueErrors.");
+"encoding defaults to the default encoding (see sys.getdefaultencoding()).\n"
+"\n"
+"errors may be given to set a different error handling scheme.  Default is\n"
+"\'strict\' meaning that encoding errors raise a ValueError.  Other possible\n"
+"values are \'ignore\', \'replace\' and \'backslashreplace\' as well as any other\n"
+"name registered with codecs.register_error that can handle ValueErrors.");
 
 #define _CODECS_ENCODE_METHODDEF    \
     {"encode", (PyCFunction)_codecs_encode, METH_VARARGS|METH_KEYWORDS, _codecs_encode__doc__},
@@ -70,7 +70,7 @@
     const char *encoding = NULL;
     const char *errors = NULL;
 
-    if (!PyArg_ParseTupleAndKeywords(args, kwargs, "O|ss:encode", _keywords,
+    if (!PyArg_ParseTupleAndKeywords(args, kwargs, "O|zs:encode", _keywords,
         &obj, &encoding, &errors))
         goto exit;
     return_value = _codecs_encode_impl(module, obj, encoding, errors);
@@ -80,17 +80,17 @@
 }
 
 PyDoc_STRVAR(_codecs_decode__doc__,
-"decode($module, /, obj, encoding=sys.getdefaultencoding(),\n"
-"       errors=\'strict\')\n"
+"decode($module, /, obj, encoding=None, errors=\'strict\')\n"
 "--\n"
 "\n"
 "Decodes obj using the codec registered for encoding.\n"
 "\n"
-"encoding defaults to the default encoding.  errors may be given to set a\n"
-"different error handling scheme.  Default is \'strict\' meaning that encoding\n"
-"errors raise a ValueError.  Other possible values are \'ignore\', \'replace\'\n"
-"and \'backslashreplace\' as well as any other name registered with\n"
-"codecs.register_error that can handle ValueErrors.");
+"encoding defaults to the default encoding (see sys.getdefaultencoding()).\n"
+"\n"
+"errors may be given to set a different error handling scheme.  Default is\n"
+"\'strict\' meaning that encoding errors raise a ValueError.  Other possible\n"
+"values are \'ignore\', \'replace\' and \'backslashreplace\' as well as any other\n"
+"name registered with codecs.register_error that can handle ValueErrors.");
 
 #define _CODECS_DECODE_METHODDEF    \
     {"decode", (PyCFunction)_codecs_decode, METH_VARARGS|METH_KEYWORDS, _codecs_decode__doc__},
@@ -108,7 +108,7 @@
     const char *encoding = NULL;
     const char *errors = NULL;
 
-    if (!PyArg_ParseTupleAndKeywords(args, kwargs, "O|ss:decode", _keywords,
+    if (!PyArg_ParseTupleAndKeywords(args, kwargs, "O|zs:decode", _keywords,
         &obj, &encoding, &errors))
         goto exit;
     return_value = _codecs_decode_impl(module, obj, encoding, errors);
@@ -1395,4 +1395,4 @@
 #ifndef _CODECS_CODE_PAGE_ENCODE_METHODDEF
     #define _CODECS_CODE_PAGE_ENCODE_METHODDEF
 #endif /* !defined(_CODECS_CODE_PAGE_ENCODE_METHODDEF) */
-/*[clinic end generated code: output=713a4081788da1bc input=a9049054013a1b77]*/
+/*[clinic end generated code: output=d00006e5f3a29a2d input=a9049054013a1b77]*/