https://bugs.gentoo.org/show_bug.cgi?id=329499
http://bugs.python.org/issue5504
http://hg.python.org/cpython/rev/e13ea83e2edb

--- Modules/_ctypes/callbacks.c
+++ Modules/_ctypes/callbacks.c
@@ -21,8 +21,8 @@
     Py_XDECREF(self->converters);
     Py_XDECREF(self->callable);
     Py_XDECREF(self->restype);
-    if (self->pcl)
-        FreeClosure(self->pcl);
+    if (self->pcl_write)
+        ffi_closure_free(self->pcl_write);
     PyObject_GC_Del(self);
 }
 
@@ -373,7 +373,8 @@
         return NULL;
     }
 
-    p->pcl = NULL;
+    p->pcl_exec = NULL;
+    p->pcl_write = NULL;
     memset(&p->cif, 0, sizeof(p->cif));
     p->converters = NULL;
     p->callable = NULL;
@@ -403,8 +404,9 @@
 
     assert(CThunk_CheckExact(p));
 
-    p->pcl = MallocClosure();
-    if (p->pcl == NULL) {
+    p->pcl_write = ffi_closure_alloc(sizeof(ffi_closure),
+                                     &p->pcl_exec);
+    if (p->pcl_write == NULL) {
         PyErr_NoMemory();
         goto error;
     }
@@ -449,7 +451,9 @@
                      "ffi_prep_cif failed with %d", result);
         goto error;
     }
-    result = ffi_prep_closure(p->pcl, &p->cif, closure_fcn, p);
+    result = ffi_prep_closure_loc(p->pcl_write, &p->cif, closure_fcn,
+                                  p,
+                                  p->pcl_exec);
     if (result != FFI_OK) {
         PyErr_Format(PyExc_RuntimeError,
                      "ffi_prep_closure failed with %d", result);
--- Modules/_ctypes/_ctypes.c
+++ Modules/_ctypes/_ctypes.c
@@ -3443,7 +3443,7 @@
     self->callable = callable;
 
     self->thunk = thunk;
-    *(void **)self->b_ptr = (void *)thunk->pcl;
+    *(void **)self->b_ptr = (void *)thunk->pcl_exec;
 
     Py_INCREF((PyObject *)thunk); /* for KeepRef */
     if (-1 == KeepRef((CDataObject *)self, 0, (PyObject *)thunk)) {
--- Modules/_ctypes/ctypes.h
+++ Modules/_ctypes/ctypes.h
@@ -95,7 +95,8 @@
 
 typedef struct {
     PyObject_VAR_HEAD
-    ffi_closure *pcl; /* the C callable */
+    ffi_closure *pcl_write; /* the C callable, writeable */
+    void *pcl_exec;         /* the C callable, executable */
     ffi_cif cif;
     int flags;
     PyObject *converters;
@@ -427,9 +428,6 @@
 
 #endif
 
-extern void FreeClosure(void *);
-extern void *MallocClosure(void);
-
 extern void _AddTraceback(char *, char *, int);
 
 extern PyObject *CData_FromBaseObj(PyObject *type, PyObject *base, Py_ssize_t index, char *adr);
--- Modules/_ctypes/malloc_closure.c
+++ Modules/_ctypes/malloc_closure.c
@@ -93,7 +93,7 @@
 /******************************************************************/
 
 /* put the item back into the free list */
-void FreeClosure(void *p)
+void ffi_closure_free(void *p)
 {
     ITEM *item = (ITEM *)p;
     item->next = free_list;
@@ -101,7 +101,7 @@
 }
 
 /* return one item from the free list, allocating more if needed */
-void *MallocClosure(void)
+void *ffi_closure_alloc(size_t ignored, void** codeloc)
 {
     ITEM *item;
     if (!free_list)
@@ -110,5 +110,7 @@
         return NULL;
     item = free_list;
     free_list = item->next;
-    return item;
+	*codeloc = (void *)item;
+    return (void *)item;
 }
+
--- setup.py
+++ setup.py
@@ -1885,8 +1885,7 @@
                    '_ctypes/callbacks.c',
                    '_ctypes/callproc.c',
                    '_ctypes/stgdict.c',
-                   '_ctypes/cfield.c',
-                   '_ctypes/malloc_closure.c']
+                   '_ctypes/cfield.c']
         depends = ['_ctypes/ctypes.h']
 
         if sys.platform == 'darwin':