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)