diff --git a/Doc/library/unittest.mock.rst b/Doc/library/unittest.mock.rst
index ed00ee6d0c2d83..a3eb3b3db5bf4f 100644
--- a/Doc/library/unittest.mock.rst
+++ b/Doc/library/unittest.mock.rst
@@ -2213,6 +2213,16 @@ And for reading files::
     >>> m.assert_called_once_with('foo')
     >>> assert result == 'bibble'
 
+If you want to mock open for use in another module you can mock
+builtins.open:
+
+    >>> with patch('builtins.open', mock_open(read_data='bibble')) as m:
+    ...     with open('foo') as h:
+    ...         result = h.read()
+    ...
+    >>> m.assert_called_once_with('foo')
+    >>> assert result == 'bibble'
+
 
 .. _auto-speccing:
 
diff --git a/Misc/NEWS.d/next/Documentation/2019-04-10-14-47-17.bpo-33722.UwwygU.rst b/Misc/NEWS.d/next/Documentation/2019-04-10-14-47-17.bpo-33722.UwwygU.rst
new file mode 100644
index 00000000000000..4cbd50fbd8adee
--- /dev/null
+++ b/Misc/NEWS.d/next/Documentation/2019-04-10-14-47-17.bpo-33722.UwwygU.rst
@@ -0,0 +1,2 @@
+Add in example to unittest.mock.rst showing how to mock builtins.open in
+cases where builtins.open is mocked in another module.