diff --git a/Lib/test/test_property.py b/Lib/test/test_property.py
index 172737a..7f3813f 100644
--- a/Lib/test/test_property.py
+++ b/Lib/test/test_property.py
@@ -204,6 +204,16 @@ def __doc__(cls):
                 return 'Second'
         self.assertEqual(A.__doc__, 'Second')
 
+    def test_property_set_name_incorrect_args(self):
+        p = property()
+
+        for i in (0, 1, 3):
+            with self.assertRaisesRegex(
+                TypeError,
+                fr'^__set_name__\(\) takes 2 positional arguments but {i} were given$'
+            ):
+                p.__set_name__(*([0] * i))
+
 
 # Issue 5890: subclasses of property do not preserve method __doc__ strings
 class PropertySub(property):
@@ -299,6 +309,46 @@ def spam(self):
         self.assertEqual(Foo.spam.__doc__, "a new docstring")
 
 
+class _PropertyUnreachableAttribute:
+    msg_format = None
+    obj = None
+    cls = None
+
+    def _format_exc_msg(self, msg):
+        return self.msg_format.format(msg)
+
+    @classmethod
+    def setUpClass(cls):
+        cls.obj = cls.cls()
+
+    def test_get_property(self):
+        with self.assertRaisesRegex(AttributeError, self._format_exc_msg("unreadable attribute")):
+            self.obj.foo
+
+    def test_set_property(self):
+        with self.assertRaisesRegex(AttributeError, self._format_exc_msg("can't set attribute")):
+            self.obj.foo = None
+
+    def test_del_property(self):
+        with self.assertRaisesRegex(AttributeError, self._format_exc_msg("can't delete attribute")):
+            del self.obj.foo
+
+
+class PropertyUnreachableAttributeWithName(_PropertyUnreachableAttribute, unittest.TestCase):
+    msg_format = "^{} 'foo'$"
+
+    class cls:
+        foo = property()
+
+
+class PropertyUnreachableAttributeNoName(_PropertyUnreachableAttribute, unittest.TestCase):
+    msg_format = "^{}$"
+
+    class cls:
+        pass
+
+    cls.foo = property()
+
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 3860656..3af5b11 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -1329,7 +1329,7 @@ def getx(self): return self.__x
             def setx(self, value): self.__x = value
             def delx(self): del self.__x
             x = property(getx, setx, delx, "")
-            check(x, size('4Pi'))
+            check(x, size('5Pi'))
         # PyCapsule
         # XXX
         # rangeiterator