diff -r 46f8188f8646 Objects/dictobject.c
--- a/Objects/dictobject.c	Fri Jan 27 13:05:09 2017 +0000
+++ b/Objects/dictobject.c	Sat Jan 28 11:45:21 2017 +0900
@@ -3331,19 +3331,17 @@
     return PyDict_SetItem(v, kv, item);
 }
 
 int
 PyDict_SetItemString(PyObject *v, const char *key, PyObject *item)
 {
-    PyObject *kv;
-    int err;
-    kv = PyUnicode_FromString(key);
-    if (kv == NULL)
+    PyObject *kv = PyUnicode_InternFromString(key);
+    if (kv == NULL) {
         return -1;
-    PyUnicode_InternInPlace(&kv); /* XXX Should we really? */
-    err = PyDict_SetItem(v, kv, item);
+    }
+    int err = PyDict_SetItem(v, kv, item);
     Py_DECREF(kv);
     return err;
 }
 
 int
 _PyDict_DelItemId(PyObject *v, _Py_Identifier *key)
diff -r 46f8188f8646 Objects/typeobject.c
--- a/Objects/typeobject.c	Fri Jan 27 13:05:09 2017 +0000
+++ b/Objects/typeobject.c	Sat Jan 28 11:45:21 2017 +0900
@@ -4535,83 +4535,117 @@
 add_methods(PyTypeObject *type, PyMethodDef *meth)
 {
     PyObject *dict = type->tp_dict;
 
     for (; meth->ml_name != NULL; meth++) {
         PyObject *descr;
-        int err;
-        if (PyDict_GetItemString(dict, meth->ml_name) &&
-            !(meth->ml_flags & METH_COEXIST))
-                continue;
+        PyObject *name = PyUnicode_FromString(meth->ml_name);
+        if (name == NULL) {
+            return -1;
+        }
+
+        if (PyDict_GetItem(dict, name) && !(meth->ml_flags & METH_COEXIST)) {
+            Py_DECREF(name);
+            continue;
+        }
+        PyUnicode_InternInPlace(&name);
+
         if (meth->ml_flags & METH_CLASS) {
             if (meth->ml_flags & METH_STATIC) {
                 PyErr_SetString(PyExc_ValueError,
                      "method cannot be both class and static");
+                Py_DECREF(name);
                 return -1;
             }
             descr = PyDescr_NewClassMethod(type, meth);
         }
         else if (meth->ml_flags & METH_STATIC) {
           PyObject *cfunc = PyCFunction_NewEx(meth, (PyObject*)type, NULL);
-            if (cfunc == NULL)
+            if (cfunc == NULL) {
+                Py_DECREF(name);
                 return -1;
+            }
             descr = PyStaticMethod_New(cfunc);
             Py_DECREF(cfunc);
         }
         else {
             descr = PyDescr_NewMethod(type, meth);
         }
-        if (descr == NULL)
+        if (descr == NULL) {
+            Py_DECREF(name);
             return -1;
-        err = PyDict_SetItemString(dict, meth->ml_name, descr);
+        }
+        int err = PyDict_SetItem(dict, name, descr);
+        Py_DECREF(name);
         Py_DECREF(descr);
-        if (err < 0)
+        if (err < 0) {
             return -1;
+        }
     }
     return 0;
 }
 
 static int
 add_members(PyTypeObject *type, PyMemberDef *memb)
 {
     PyObject *dict = type->tp_dict;
 
     for (; memb->name != NULL; memb++) {
-        PyObject *descr;
-        if (PyDict_GetItemString(dict, memb->name))
+        PyObject *name = PyUnicode_FromString(memb->name);
+        if (name == NULL) {
+            return -1;
+        }
+
+        if (PyDict_GetItem(dict, name)) {
+            Py_DECREF(name);
             continue;
-        descr = PyDescr_NewMember(type, memb);
-        if (descr == NULL)
+        }
+        PyUnicode_InternInPlace(&name);
+
+        PyObject *descr = PyDescr_NewMember(type, memb);
+        if (descr == NULL) {
+            Py_DECREF(name);
             return -1;
-        if (PyDict_SetItemString(dict, memb->name, descr) < 0) {
-            Py_DECREF(descr);
+        }
+
+        int err = PyDict_SetItem(dict, name, descr);
+        Py_DECREF(name);
+        Py_DECREF(descr);
+        if (err) {
             return -1;
         }
-        Py_DECREF(descr);
     }
     return 0;
 }
 
 static int
 add_getset(PyTypeObject *type, PyGetSetDef *gsp)
 {
     PyObject *dict = type->tp_dict;
 
     for (; gsp->name != NULL; gsp++) {
-        PyObject *descr;
-        if (PyDict_GetItemString(dict, gsp->name))
+        PyObject *name = PyUnicode_FromString(gsp->name);
+        if (name == NULL) {
+            return -1;
+        }
+        if (PyDict_GetItem(dict, name)) {
+            Py_DECREF(name);
             continue;
-        descr = PyDescr_NewGetSet(type, gsp);
-
-        if (descr == NULL)
+        }
+        PyUnicode_InternInPlace(&name);
+
+        PyObject *descr = PyDescr_NewGetSet(type, gsp);
+        if (descr == NULL) {
             return -1;
-        if (PyDict_SetItemString(dict, gsp->name, descr) < 0) {
-            Py_DECREF(descr);
+        }
+        int err = PyDict_SetItem(dict, name, descr);
+        Py_DECREF(name);
+        Py_DECREF(descr);
+        if (err) {
             return -1;
         }
-        Py_DECREF(descr);
     }
     return 0;
 }
 
 static void
 inherit_special(PyTypeObject *type, PyTypeObject *base)