diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py
index 21c7b8c..b5a10ed 100644
--- a/Lib/test/test_descr.py
+++ b/Lib/test/test_descr.py
@@ -4502,6 +4502,14 @@
         self.assertEqual(float.real.__qualname__, 'float.real')
         self.assertEqual(int.__add__.__qualname__, 'int.__add__')
 
+        class X:
+            pass
+        with self.assertRaises(TypeError):
+            del X.__qualname__
+
+        self.assertRaises(TypeError, type.__dict__['__qualname__'].__set__,
+                          str, 'Oink')
+
     def test_qualname_dict(self):
         ns = {'__qualname__': 'some.name'}
         tp = type('Foo', (), ns)
diff --git a/Misc/NEWS b/Misc/NEWS
index 726d1f7..347885f 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,9 @@
 Core and Builtins
 -----------------
 
+- Fix segfaults on setting __qualname__ on builtin types and attempting to
+  delete it on any type.
+
 - Issue #16271: Fix strange bugs that resulted from __qualname__ appearing in a
   class's __dict__ and on type.
 
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 9f0d13e..413c7da 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -311,6 +311,8 @@
 {
     PyHeapTypeObject* et;
 
+    if (!check_set_special_type_attr(type, value, "__qualname__"))
+        return -1;
     if (!PyUnicode_Check(value)) {
         PyErr_Format(PyExc_TypeError,
                      "can only assign string to %s.__qualname__, not '%s'",