diff -r a62072cf50a2 Modules/_collectionsmodule.c
--- a/Modules/_collectionsmodule.c	Wed Jan 22 12:26:01 2014 +0100
+++ b/Modules/_collectionsmodule.c	Wed Jan 22 15:23:06 2014 +0200
@@ -7,6 +7,22 @@
    All rights reserved.
 */
 
+/*[clinic input]
+module collections
+module _collections
+class collections.deque
+class collections.Counter
+class _collections.dequeiter
+class _collections.dequereviter
+[clinic start generated code]*/
+/*[clinic end generated code: checksum=da39a3ee5e6b4b0d3255bfef95601890afd80709]*/
+
+/*[python input]
+class dequeobject_converter(self_converter):
+    type = "dequeobject *"
+[python start generated code]*/
+/*[python end generated code: checksum=da39a3ee5e6b4b0d3255bfef95601890afd80709]*/
+
 /* The block length may be set to any number over 1.  Larger numbers
  * reduce the number of calls to the memory allocator, give faster
  * indexing and rotation, and reduce the link::data overhead ratio.
@@ -1026,29 +1042,57 @@
     return NULL;
 }
 
+/*[clinic input]
+collections.deque.__init__ as deque_init
+
+    self: self(type="dequeobject *")
+    iterable: object = NULL
+    maxlen: Py_ssize_t(nullable=True) = None
+
+Build an ordered collection with optimized access from its endpoints.
+[clinic start generated code]*/
+
+PyDoc_STRVAR(deque_init__doc__,
+"deque(iterable=None, maxlen=None)\n"
+"Build an ordered collection with optimized access from its endpoints.");
+
 static int
-deque_init(dequeobject *deque, PyObject *args, PyObject *kwdargs)
+deque_init_impl(dequeobject *self, PyObject *iterable, nullable_Py_ssize_t *maxlen);
+
+static int
+deque_init(PyObject *self, PyObject *args, PyObject *kwargs)
 {
+    int return_value = -1;
+    static char *_keywords[] = {"iterable", "maxlen", NULL};
     PyObject *iterable = NULL;
-    PyObject *maxlenobj = NULL;
-    Py_ssize_t maxlen = -1;
-    char *kwlist[] = {"iterable", "maxlen", 0};
+    nullable_Py_ssize_t maxlen = NULLABLE_PY_SSIZE_T_INITIALIZE(0, 1);
 
-    if (!PyArg_ParseTupleAndKeywords(args, kwdargs, "|OO:deque", kwlist, &iterable, &maxlenobj))
+    if (!PyArg_ParseTupleAndKeywords(args, kwargs,
+        "|OO&:__init__", _keywords,
+        &iterable, _PyLong_NullablePy_ssize_tConverter, &maxlen))
+        goto exit;
+    return_value = deque_init_impl((dequeobject *)self, iterable, &maxlen);
+
+exit:
+    return return_value;
+}
+
+static int
+deque_init_impl(dequeobject *self, PyObject *iterable, nullable_Py_ssize_t *maxlen)
+/*[clinic end generated code: checksum=3b1ffeeee9a70ec1573dfebf813d3d9b13b68c68]*/
+{
+    if (!maxlen->is_null && maxlen->i < 0) {
+        PyErr_SetString(PyExc_ValueError, "maxlen must be non-negative");
         return -1;
-    if (maxlenobj != NULL && maxlenobj != Py_None) {
-        maxlen = PyLong_AsSsize_t(maxlenobj);
-        if (maxlen == -1 && PyErr_Occurred())
-            return -1;
-        if (maxlen < 0) {
-            PyErr_SetString(PyExc_ValueError, "maxlen must be non-negative");
-            return -1;
-        }
     }
-    deque->maxlen = maxlen;
-    deque_clear(deque);
+
+    if (maxlen->is_null)
+        self->maxlen = -1;
+    else
+        self->maxlen = maxlen->i;
+    deque_clear(self);
     if (iterable != NULL) {
-        PyObject *rv = deque_extend(deque, iterable);
+        PyObject *rv = deque_extend(self, iterable);
         if (rv == NULL)
             return -1;
         Py_DECREF(rv);
@@ -1142,11 +1186,6 @@
     {NULL,              NULL}   /* sentinel */
 };
 
-PyDoc_STRVAR(deque_doc,
-"deque([iterable[, maxlen]]) --> deque object\n\
-\n\
-Build an ordered collection with optimized access from its endpoints.");
-
 static PyTypeObject deque_type = {
     PyVarObject_HEAD_INIT(NULL, 0)
     "collections.deque",                /* tp_name */
@@ -1170,7 +1209,7 @@
     0,                                  /* tp_as_buffer */
     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC,
                                         /* tp_flags */
-    deque_doc,                          /* tp_doc */
+    deque_init__doc__,                  /* tp_doc */
     (traverseproc)deque_traverse,       /* tp_traverse */
     (inquiry)deque_clear,               /* tp_clear */
     (richcmpfunc)deque_richcompare,     /* tp_richcompare */