diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index fb9868b3740b8c..46a6fd9a8ef017 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -494,6 +494,8 @@ typedef struct {
     PyObject *it;
 } filterobject;
 
+#define _filterobject_CAST(op)      ((filterobject *)(op))
+
 static PyObject *
 filter_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 {
@@ -559,8 +561,9 @@ filter_vectorcall(PyObject *type, PyObject * const*args,
 }
 
 static void
-filter_dealloc(filterobject *lz)
+filter_dealloc(PyObject *self)
 {
+    filterobject *lz = _filterobject_CAST(self);
     PyObject_GC_UnTrack(lz);
     Py_TRASHCAN_BEGIN(lz, filter_dealloc)
     Py_XDECREF(lz->func);
@@ -570,16 +573,18 @@ filter_dealloc(filterobject *lz)
 }
 
 static int
-filter_traverse(filterobject *lz, visitproc visit, void *arg)
+filter_traverse(PyObject *self, visitproc visit, void *arg)
 {
+    filterobject *lz = _filterobject_CAST(self);
     Py_VISIT(lz->it);
     Py_VISIT(lz->func);
     return 0;
 }
 
 static PyObject *
-filter_next(filterobject *lz)
+filter_next(PyObject *self)
 {
+    filterobject *lz = _filterobject_CAST(self);
     PyObject *item;
     PyObject *it = lz->it;
     long ok;
@@ -613,15 +618,16 @@ filter_next(filterobject *lz)
 }
 
 static PyObject *
-filter_reduce(filterobject *lz, PyObject *Py_UNUSED(ignored))
+filter_reduce(PyObject *self, PyObject *Py_UNUSED(ignored))
 {
+    filterobject *lz = _filterobject_CAST(self);
     return Py_BuildValue("O(OO)", Py_TYPE(lz), lz->func, lz->it);
 }
 
 PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");
 
 static PyMethodDef filter_methods[] = {
-    {"__reduce__", _PyCFunction_CAST(filter_reduce), METH_NOARGS, reduce_doc},
+    {"__reduce__", filter_reduce, METH_NOARGS, reduce_doc},
     {NULL,           NULL}           /* sentinel */
 };
 
@@ -638,7 +644,7 @@ PyTypeObject PyFilter_Type = {
     sizeof(filterobject),               /* tp_basicsize */
     0,                                  /* tp_itemsize */
     /* methods */
-    (destructor)filter_dealloc,         /* tp_dealloc */
+    filter_dealloc,                     /* tp_dealloc */
     0,                                  /* tp_vectorcall_offset */
     0,                                  /* tp_getattr */
     0,                                  /* tp_setattr */
@@ -656,12 +662,12 @@ PyTypeObject PyFilter_Type = {
     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
         Py_TPFLAGS_BASETYPE,            /* tp_flags */
     filter_doc,                         /* tp_doc */
-    (traverseproc)filter_traverse,      /* tp_traverse */
+    filter_traverse,                    /* tp_traverse */
     0,                                  /* tp_clear */
     0,                                  /* tp_richcompare */
     0,                                  /* tp_weaklistoffset */
     PyObject_SelfIter,                  /* tp_iter */
-    (iternextfunc)filter_next,          /* tp_iternext */
+    filter_next,                        /* tp_iternext */
     filter_methods,                     /* tp_methods */
     0,                                  /* tp_members */
     0,                                  /* tp_getset */
@@ -674,7 +680,7 @@ PyTypeObject PyFilter_Type = {
     PyType_GenericAlloc,                /* tp_alloc */
     filter_new,                         /* tp_new */
     PyObject_GC_Del,                    /* tp_free */
-    .tp_vectorcall = (vectorcallfunc)filter_vectorcall
+    .tp_vectorcall = filter_vectorcall
 };
 
 
@@ -1319,6 +1325,8 @@ typedef struct {
     int strict;
 } mapobject;
 
+#define _mapobject_CAST(op)     ((mapobject *)(op))
+
 static PyObject *
 map_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 {
@@ -1422,8 +1430,9 @@ map_vectorcall(PyObject *type, PyObject * const*args,
 }
 
 static void
-map_dealloc(mapobject *lz)
+map_dealloc(PyObject *self)
 {
+    mapobject *lz = _mapobject_CAST(self);
     PyObject_GC_UnTrack(lz);
     Py_XDECREF(lz->iters);
     Py_XDECREF(lz->func);
@@ -1431,16 +1440,18 @@ map_dealloc(mapobject *lz)
 }
 
 static int
-map_traverse(mapobject *lz, visitproc visit, void *arg)
+map_traverse(PyObject *self, visitproc visit, void *arg)
 {
+    mapobject *lz = _mapobject_CAST(self);
     Py_VISIT(lz->iters);
     Py_VISIT(lz->func);
     return 0;
 }
 
 static PyObject *
-map_next(mapobject *lz)
+map_next(PyObject *self)
 {
+    mapobject *lz = _mapobject_CAST(self);
     Py_ssize_t i;
     PyObject *small_stack[_PY_FASTCALL_SMALL_STACK];
     PyObject **stack;
@@ -1523,8 +1534,9 @@ map_next(mapobject *lz)
 }
 
 static PyObject *
-map_reduce(mapobject *lz, PyObject *Py_UNUSED(ignored))
+map_reduce(PyObject *self, PyObject *Py_UNUSED(ignored))
 {
+    mapobject *lz = _mapobject_CAST(self);
     Py_ssize_t numargs = PyTuple_GET_SIZE(lz->iters);
     PyObject *args = PyTuple_New(numargs+1);
     Py_ssize_t i;
@@ -1545,19 +1557,20 @@ map_reduce(mapobject *lz, PyObject *Py_UNUSED(ignored))
 PyDoc_STRVAR(setstate_doc, "Set state information for unpickling.");
 
 static PyObject *
-map_setstate(mapobject *lz, PyObject *state)
+map_setstate(PyObject *self, PyObject *state)
 {
     int strict = PyObject_IsTrue(state);
     if (strict < 0) {
         return NULL;
     }
+    mapobject *lz = _mapobject_CAST(self);
     lz->strict = strict;
     Py_RETURN_NONE;
 }
 
 static PyMethodDef map_methods[] = {
-    {"__reduce__", _PyCFunction_CAST(map_reduce), METH_NOARGS, reduce_doc},
-    {"__setstate__", _PyCFunction_CAST(map_setstate), METH_O, setstate_doc},
+    {"__reduce__", map_reduce, METH_NOARGS, reduce_doc},
+    {"__setstate__", map_setstate, METH_O, setstate_doc},
     {NULL,           NULL}           /* sentinel */
 };
 
@@ -1578,7 +1591,7 @@ PyTypeObject PyMap_Type = {
     sizeof(mapobject),                  /* tp_basicsize */
     0,                                  /* tp_itemsize */
     /* methods */
-    (destructor)map_dealloc,            /* tp_dealloc */
+    map_dealloc,                        /* tp_dealloc */
     0,                                  /* tp_vectorcall_offset */
     0,                                  /* tp_getattr */
     0,                                  /* tp_setattr */
@@ -1596,12 +1609,12 @@ PyTypeObject PyMap_Type = {
     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
         Py_TPFLAGS_BASETYPE,            /* tp_flags */
     map_doc,                            /* tp_doc */
-    (traverseproc)map_traverse,         /* tp_traverse */
+    map_traverse,                       /* tp_traverse */
     0,                                  /* tp_clear */
     0,                                  /* tp_richcompare */
     0,                                  /* tp_weaklistoffset */
     PyObject_SelfIter,                  /* tp_iter */
-    (iternextfunc)map_next,     /* tp_iternext */
+    map_next,                           /* tp_iternext */
     map_methods,                        /* tp_methods */
     0,                                  /* tp_members */
     0,                                  /* tp_getset */
@@ -1614,7 +1627,7 @@ PyTypeObject PyMap_Type = {
     PyType_GenericAlloc,                /* tp_alloc */
     map_new,                            /* tp_new */
     PyObject_GC_Del,                    /* tp_free */
-    .tp_vectorcall = (vectorcallfunc)map_vectorcall
+    .tp_vectorcall = map_vectorcall
 };
 
 
@@ -2965,6 +2978,8 @@ typedef struct {
     int strict;
 } zipobject;
 
+#define _zipobject_CAST(op)     ((zipobject *)(op))
+
 static PyObject *
 zip_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 {
@@ -3033,8 +3048,9 @@ zip_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 }
 
 static void
-zip_dealloc(zipobject *lz)
+zip_dealloc(PyObject *self)
 {
+    zipobject *lz = _zipobject_CAST(self);
     PyObject_GC_UnTrack(lz);
     Py_XDECREF(lz->ittuple);
     Py_XDECREF(lz->result);
@@ -3042,16 +3058,19 @@ zip_dealloc(zipobject *lz)
 }
 
 static int
-zip_traverse(zipobject *lz, visitproc visit, void *arg)
+zip_traverse(PyObject *self, visitproc visit, void *arg)
 {
+    zipobject *lz = _zipobject_CAST(self);
     Py_VISIT(lz->ittuple);
     Py_VISIT(lz->result);
     return 0;
 }
 
 static PyObject *
-zip_next(zipobject *lz)
+zip_next(PyObject *self)
 {
+    zipobject *lz = _zipobject_CAST(self);
+
     Py_ssize_t i;
     Py_ssize_t tuplesize = lz->tuplesize;
     PyObject *result = lz->result;
@@ -3141,8 +3160,9 @@ zip_next(zipobject *lz)
 }
 
 static PyObject *
-zip_reduce(zipobject *lz, PyObject *Py_UNUSED(ignored))
+zip_reduce(PyObject *self, PyObject *Py_UNUSED(ignored))
 {
+    zipobject *lz = _zipobject_CAST(self);
     /* Just recreate the zip with the internal iterator tuple */
     if (lz->strict) {
         return PyTuple_Pack(3, Py_TYPE(lz), lz->ittuple, Py_True);
@@ -3151,19 +3171,20 @@ zip_reduce(zipobject *lz, PyObject *Py_UNUSED(ignored))
 }
 
 static PyObject *
-zip_setstate(zipobject *lz, PyObject *state)
+zip_setstate(PyObject *self, PyObject *state)
 {
     int strict = PyObject_IsTrue(state);
     if (strict < 0) {
         return NULL;
     }
+    zipobject *lz = _zipobject_CAST(self);
     lz->strict = strict;
     Py_RETURN_NONE;
 }
 
 static PyMethodDef zip_methods[] = {
-    {"__reduce__", _PyCFunction_CAST(zip_reduce), METH_NOARGS, reduce_doc},
-    {"__setstate__", _PyCFunction_CAST(zip_setstate), METH_O, setstate_doc},
+    {"__reduce__", zip_reduce, METH_NOARGS, reduce_doc},
+    {"__setstate__", zip_setstate, METH_O, setstate_doc},
     {NULL}  /* sentinel */
 };
 
@@ -3188,7 +3209,7 @@ PyTypeObject PyZip_Type = {
     sizeof(zipobject),                  /* tp_basicsize */
     0,                                  /* tp_itemsize */
     /* methods */
-    (destructor)zip_dealloc,            /* tp_dealloc */
+    zip_dealloc,                        /* tp_dealloc */
     0,                                  /* tp_vectorcall_offset */
     0,                                  /* tp_getattr */
     0,                                  /* tp_setattr */
@@ -3206,12 +3227,12 @@ PyTypeObject PyZip_Type = {
     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
         Py_TPFLAGS_BASETYPE,            /* tp_flags */
     zip_doc,                            /* tp_doc */
-    (traverseproc)zip_traverse,    /* tp_traverse */
+    zip_traverse,                       /* tp_traverse */
     0,                                  /* tp_clear */
     0,                                  /* tp_richcompare */
     0,                                  /* tp_weaklistoffset */
     PyObject_SelfIter,                  /* tp_iter */
-    (iternextfunc)zip_next,     /* tp_iternext */
+    zip_next,                           /* tp_iternext */
     zip_methods,                        /* tp_methods */
     0,                                  /* tp_members */
     0,                                  /* tp_getset */