diff -r a45cb181e4d0 Objects/longobject.c
--- a/Objects/longobject.c	Wed Oct 17 20:29:07 2012 -0700
+++ b/Objects/longobject.c	Thu Oct 18 22:03:11 2012 +0300
@@ -935,17 +935,19 @@
 PyObject *
 PyLong_FromVoidPtr(void *p)
 {
+    /* always convert NULL to 0 */
+    Py_uintptr_t x = (Py_uintptr_t)p - (Py_uintptr_t)(void *)NULL;
+#if SIZEOF_VOID_P <= SIZEOF_LONG
+    return PyLong_FromUnsignedLong((unsigned long)x);
+#else
 #ifndef HAVE_LONG_LONG
 #   error "PyLong_FromVoidPtr: sizeof(void*) > sizeof(long), but no long long"
 #endif
 #if SIZEOF_LONG_LONG < SIZEOF_VOID_P
 #   error "PyLong_FromVoidPtr: sizeof(PY_LONG_LONG) < sizeof(void*)"
 #endif
-    /* special-case null pointer */
-    if (!p)
-        return PyLong_FromLong(0);
-    return PyLong_FromUnsignedLongLong((unsigned PY_LONG_LONG)(Py_uintptr_t)p);
-
+    return PyLong_FromUnsignedLongLong((unsigned PY_LONG_LONG)x);
+#endif /* SIZEOF_VOID_P <= SIZEOF_LONG */
 }
 
 /* Get a C pointer from a long int object. */
@@ -979,7 +981,8 @@
 
     if (x == -1 && PyErr_Occurred())
         return NULL;
-    return (void *)x;
+    /* always convert 0 to NULL */
+    return (void *)((Py_uintptr_t)x + (Py_uintptr_t)(void *)NULL);
 }
 
 #ifdef HAVE_LONG_LONG