diff -r 770ffc91a82e Include/dictobject.h
--- a/Include/dictobject.h	Thu Aug 16 07:22:15 2012 +0300
+++ b/Include/dictobject.h	Thu Aug 16 22:11:53 2012 +0300
@@ -129,6 +129,7 @@
 PyAPI_FUNC(PyObject *) _PyDict_NewPresized(Py_ssize_t minused);
 PyAPI_FUNC(void) _PyDict_MaybeUntrack(PyObject *mp);
 PyAPI_FUNC(int) _PyDict_HasOnlyStringKeys(PyObject *mp);
+PyAPI_FUNC(Py_ssize_t) _PyDict_SizeOf(PyDictObject *mp);
 #endif
 
 /* PyDict_Update(mp, other) is equivalent to PyDict_Merge(mp, other, 1). */
diff -r 770ffc91a82e Modules/_ctypes/stgdict.c
--- a/Modules/_ctypes/stgdict.c	Thu Aug 16 07:22:15 2012 +0300
+++ b/Modules/_ctypes/stgdict.c	Thu Aug 16 22:11:53 2012 +0300
@@ -48,6 +48,21 @@
     PyDict_Type.tp_dealloc((PyObject *)self);
 }
 
+static PyObject *
+PyCStgDict_sizeof(StgDictObject *self, void *unused)
+{
+    Py_ssize_t res;
+
+    res = _PyDict_SizeOf((PyDictObject *)self);
+    res += sizeof(StgDictObject) - sizeof(PyDictObject);
+    if (self->format)
+        res += strlen(self->format) + 1;
+    res += self->ndim * sizeof(Py_ssize_t);
+    if (self->ffi_type_pointer.elements)
+        res += (self->length + 1) * sizeof(ffi_type *);
+    return PyLong_FromSsize_t(res);
+}
+
 int
 PyCStgDict_clone(StgDictObject *dst, StgDictObject *src)
 {
@@ -102,6 +117,11 @@
     return 0;
 }
 
+static struct PyMethodDef PyCStgDict_methods[] = {
+    {"__sizeof__", (PyCFunction)PyCStgDict_sizeof, METH_NOARGS},
+    {NULL, NULL}                /* sentinel */
+};
+
 PyTypeObject PyCStgDict_Type = {
     PyVarObject_HEAD_INIT(NULL, 0)
     "StgDict",
@@ -130,7 +150,7 @@
     0,                                          /* tp_weaklistoffset */
     0,                                          /* tp_iter */
     0,                                          /* tp_iternext */
-    0,                                          /* tp_methods */
+    PyCStgDict_methods,                         /* tp_methods */
     0,                                          /* tp_members */
     0,                                          /* tp_getset */
     0,                                          /* tp_base */
@@ -482,7 +502,7 @@
             char *fieldfmt = dict->format ? dict->format : "B";
             char *fieldname = _PyUnicode_AsString(name);
             char *ptr;
-            Py_ssize_t len; 
+            Py_ssize_t len;
             char *buf;
 
             if (fieldname == NULL)
diff -r 770ffc91a82e Objects/dictobject.c
--- a/Objects/dictobject.c	Thu Aug 16 07:22:15 2012 +0300
+++ b/Objects/dictobject.c	Thu Aug 16 22:11:53 2012 +0300
@@ -1967,15 +1967,21 @@
 
 static PyObject *dictiter_new(PyDictObject *, PyTypeObject *);
 
-static PyObject *
-dict_sizeof(PyDictObject *mp)
+Py_ssize_t
+_PyDict_SizeOf(PyDictObject *mp)
 {
     Py_ssize_t res;
 
     res = sizeof(PyDictObject);
     if (mp->ma_table != mp->ma_smalltable)
         res = res + (mp->ma_mask + 1) * sizeof(PyDictEntry);
-    return PyLong_FromSsize_t(res);
+    return res;
+}
+
+static PyObject *
+dict_sizeof(PyDictObject *mp)
+{
+    return PyLong_FromSsize_t(_PyDict_SizeOf(mp));
 }
 
 PyDoc_STRVAR(contains__doc__,