diff -r b02d256b8827 Objects/typeobject.c
--- a/Objects/typeobject.c	Sun Dec 27 15:51:32 2015 +0200
+++ b/Objects/typeobject.c	Sun Dec 27 19:51:38 2015 +0200
@@ -420,7 +420,7 @@ type_set_name(PyTypeObject *type, PyObje
     if (PyUnicode_Contains(value, tmp) != 0) {
         Py_DECREF(tmp);
         PyErr_Format(PyExc_ValueError,
-                     "__name__ must not contain null bytes");
+                     "__name__ must not contain null characters");
         return -1;
     }
     Py_DECREF(tmp);
@@ -2284,8 +2284,8 @@ type_new(PyTypeObject *metatype, PyObjec
     PyTypeObject *type = NULL, *base, *tmptype, *winner;
     PyHeapTypeObject *et;
     PyMemberDef *mp;
-    Py_ssize_t i, nbases, nslots, slotoffset, add_dict, add_weak;
-    int j, may_add_dict, may_add_weak;
+    Py_ssize_t i, nbases, nslots, slotoffset, tp_name_size;
+    int j, may_add_dict, may_add_weak, add_dict, add_weak;
     _Py_IDENTIFIER(__qualname__);
     _Py_IDENTIFIER(__slots__);
 
@@ -2508,9 +2508,14 @@ type_new(PyTypeObject *metatype, PyObjec
     type->tp_as_sequence = &et->as_sequence;
     type->tp_as_mapping = &et->as_mapping;
     type->tp_as_buffer = &et->as_buffer;
-    type->tp_name = _PyUnicode_AsString(name);
+    type->tp_name = PyUnicode_AsUTF8AndSize(name, &tp_name_size);
     if (!type->tp_name)
         goto error;
+    if (strlen(type->tp_name) != (size_t)tp_name_size) {
+        PyErr_Format(PyExc_ValueError,
+                     "name must not contain null characters");
+        goto error;
+    }
 
     /* Set tp_base and tp_bases */
     type->tp_bases = bases;