#17881: merge with 3.3.
diff --git a/Doc/library/plistlib.rst b/Doc/library/plistlib.rst
index ae5e94d..a267368 100644
--- a/Doc/library/plistlib.rst
+++ b/Doc/library/plistlib.rst
@@ -47,8 +47,8 @@
.. function:: readPlist(pathOrFile)
- Read a plist file. *pathOrFile* may either be a file name or a (readable)
- file object. Return the unpacked root object (which usually is a
+ Read a plist file. *pathOrFile* may either be a file name or a (readable and
+ binary) file object. Return the unpacked root object (which usually is a
dictionary).
The XML data is parsed using the Expat parser from :mod:`xml.parsers.expat`
@@ -59,7 +59,7 @@
.. function:: writePlist(rootObject, pathOrFile)
Write *rootObject* to a plist file. *pathOrFile* may either be a file name
- or a (writable) file object.
+ or a (writable and binary) file object.
A :exc:`TypeError` will be raised if the object is of an unsupported type or
a container that contains objects of unsupported types.