diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index c12cd7ca32a..8cfa8894b0c 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -458,11 +458,11 @@ type_set_bases(PyTypeObject *type, PyObject *value, void *context)
     for (i = 0; i < PyTuple_GET_SIZE(value); i++) {
         ob = PyTuple_GET_ITEM(value, i);
         if (!PyType_Check(ob)) {
-            PyErr_Format(
-                PyExc_TypeError,
-    "%s.__bases__ must be tuple of old- or new-style classes, not '%s'",
-                            type->tp_name, Py_TYPE(ob)->tp_name);
-                    return -1;
+            PyErr_Format(PyExc_TypeError,
+                         "%s.__bases__ must be tuple of old- or "
+                         "new-style classes, not '%s'",
+                         type->tp_name, Py_TYPE(ob)->tp_name);
+            return -1;
         }
         if (PyType_IsSubtype((PyTypeObject*)ob, type)) {
             PyErr_SetString(PyExc_TypeError,