diff --git a/Doc/library/stdtypes.rst b/Doc/library/stdtypes.rst
index e71ce75b832..efa0a89490e 100644
--- a/Doc/library/stdtypes.rst
+++ b/Doc/library/stdtypes.rst
@@ -197,8 +197,8 @@ exception.
    operator: not in
 
 Two more operations with the same syntactic priority, :keyword:`in` and
-:keyword:`not in`, are supported only by sequence types (below).
-
+:keyword:`not in`, are supported by types that are :term:`iterable` or
+implement the :meth:`__contains__` method.
 
 .. _typesnumeric:
 
diff --git a/Misc/NEWS.d/next/Documentation/2018-09-06-22-39-47.bpo-28617.MjnJLz.rst b/Misc/NEWS.d/next/Documentation/2018-09-06-22-39-47.bpo-28617.MjnJLz.rst
new file mode 100644
index 00000000000..281afad71d2
--- /dev/null
+++ b/Misc/NEWS.d/next/Documentation/2018-09-06-22-39-47.bpo-28617.MjnJLz.rst
@@ -0,0 +1,2 @@
+Fixed info in the stdtypes docs concerning the types that support membership
+tests.