diff -r a507882736b2 Parser/asdl_c.py
--- a/Parser/asdl_c.py	Wed Jan 25 22:33:43 2017 +0900
+++ b/Parser/asdl_c.py	Thu Jan 26 00:46:36 2017 +0900
@@ -776,12 +776,19 @@
 
 
 static PyTypeObject* make_type(char *type, PyTypeObject* base, char**fields, int num_fields)
 {
     _Py_IDENTIFIER(__module__);
     _Py_IDENTIFIER(_ast);
+    PyObject *id_fields = _PyUnicode_FromId(&PyId__fields);
+    PyObject *id_module = _PyUnicode_FromId(&PyId___module__);
+    PyObject *id_ast = _PyUnicode_FromId(&PyId__ast);
+    if (id_fields == NULL || id_module == NULL || id_ast == NULL) {
+        return NULL;
+    }
+
     PyObject *fnames, *result;
     int i;
     fnames = PyTuple_New(num_fields);
     if (!fnames) return NULL;
     for (i = 0; i < num_fields; i++) {
         PyObject *field = PyUnicode_FromString(fields[i]);
@@ -789,16 +796,13 @@
             Py_DECREF(fnames);
             return NULL;
         }
         PyTuple_SET_ITEM(fnames, i, field);
     }
     result = PyObject_CallFunction((PyObject*)&PyType_Type, "s(O){OOOO}",
-                    type, base,
-                    _PyUnicode_FromId(&PyId__fields), fnames,
-                    _PyUnicode_FromId(&PyId___module__),
-                    _PyUnicode_FromId(&PyId__ast));
+                    type, base, id_fields, fnames, id_module, id_ast);
     Py_DECREF(fnames);
     return (PyTypeObject*)result;
 }
 
 static int add_attributes(PyTypeObject* type, char**attrs, int num_fields)
 {
diff -r a507882736b2 Python/Python-ast.c
--- a/Python/Python-ast.c	Wed Jan 25 22:33:43 2017 +0900
+++ b/Python/Python-ast.c	Thu Jan 26 00:46:36 2017 +0900
@@ -658,12 +658,19 @@
 
 
 static PyTypeObject* make_type(char *type, PyTypeObject* base, char**fields, int num_fields)
 {
     _Py_IDENTIFIER(__module__);
     _Py_IDENTIFIER(_ast);
+    PyObject *id_fields = _PyUnicode_FromId(&PyId__fields);
+    PyObject *id_module = _PyUnicode_FromId(&PyId___module__);
+    PyObject *id_ast = _PyUnicode_FromId(&PyId__ast);
+    if (id_fields == NULL || id_module == NULL || id_ast == NULL) {
+        return NULL;
+    }
+
     PyObject *fnames, *result;
     int i;
     fnames = PyTuple_New(num_fields);
     if (!fnames) return NULL;
     for (i = 0; i < num_fields; i++) {
         PyObject *field = PyUnicode_FromString(fields[i]);
@@ -671,16 +678,13 @@
             Py_DECREF(fnames);
             return NULL;
         }
         PyTuple_SET_ITEM(fnames, i, field);
     }
     result = PyObject_CallFunction((PyObject*)&PyType_Type, "s(O){OOOO}",
-                    type, base,
-                    _PyUnicode_FromId(&PyId__fields), fnames,
-                    _PyUnicode_FromId(&PyId___module__),
-                    _PyUnicode_FromId(&PyId__ast));
+                    type, base, id_fields, fnames, id_module, id_ast);
     Py_DECREF(fnames);
     return (PyTypeObject*)result;
 }
 
 static int add_attributes(PyTypeObject* type, char**attrs, int num_fields)
 {