diff -r 784fea019cab Lib/test/test_descr.py
--- a/Lib/test/test_descr.py	Wed Nov 09 18:57:00 2016 -0500
+++ b/Lib/test/test_descr.py	Thu Nov 10 22:18:41 2016 +0800
@@ -1284,7 +1284,7 @@
             del X().a
 
     def test_slots_special(self):
-        # Testing __dict__ and __weakref__ in __slots__...
+        # Testing special slots like __dict__ and __weakref__ in __slots__
         class D(object):
             __slots__ = ["__dict__"]
         a = D()
@@ -1305,6 +1305,32 @@
         else:
             self.fail("shouldn't be allowed to set a.foo")
 
+        class Q:
+            __slots__ = ["__qualname__"]
+        a = Q()
+        self.assertNotHasAttr(a, "__qualname__")
+        a.__qualname__ = "a"
+        self.assertEqual(a.__qualname__, "a")
+        self.assertEqual(Q.__qualname__, D.__qualname__[:-1] + "Q")
+
+        class L1:
+            def __init__(self):
+                self.b = 42
+        class L2(L1):
+            __slots__ = ["__classcell__"]
+            def __init__(self):
+                super().__init__()
+        a = L2()
+        self.assertEqual(a.b, 42)
+        self.assertNotHasAttr(a, "__classcell__")
+        a.__classcell__ = 42
+        self.assertEqual(a.__classcell__, 42)
+
+        with self.assertRaises(ValueError):
+            class L3:
+                __classcell__ = 42
+                __slots__ = ["__classcell__"]
+
         class C1(W, D):
             __slots__ = []
         a = C1()
diff -r 784fea019cab Objects/typeobject.c
--- a/Objects/typeobject.c	Wed Nov 09 18:57:00 2016 -0500
+++ b/Objects/typeobject.c	Thu Nov 10 22:18:41 2016 +0800
@@ -2445,11 +2445,27 @@
             }
             PyList_SET_ITEM(newslots, j, tmp);
             if (PyDict_GetItem(dict, tmp)) {
-                PyErr_Format(PyExc_ValueError,
-                             "%R in __slots__ conflicts with class variable",
-                             tmp);
-                Py_DECREF(newslots);
-                goto error;
+                int err = 1;
+                /* CPython inserts __qualname__ and __classcell__ (when needed)
+                   into the namespace when creating a class. They will be deleted
+                   below so won't act as a class variable. */
+                if (_PyUnicode_CompareWithId(tmp, &PyId___qualname__) == 0)
+                    err = 0;
+                if (_PyUnicode_CompareWithId(tmp, &PyId___classcell__) == 0) {
+                    cell = _PyDict_GetItemId(dict, &PyId___classcell__);
+                    if (cell != NULL && PyCell_Check(cell))
+                        err = 0;
+                    else
+                        err = 1;
+                }
+
+                if (err) {
+                    PyErr_Format(PyExc_ValueError,
+                                 "%R in __slots__ conflicts with class variable",
+                                 tmp);
+                    Py_DECREF(newslots);
+                    goto error;
+                }
             }
             j++;
         }