diff --git a/Doc/tutorial/inputoutput.rst b/Doc/tutorial/inputoutput.rst
index 6f9c99d..c157f22 100644
--- a/Doc/tutorial/inputoutput.rst
+++ b/Doc/tutorial/inputoutput.rst
@@ -247,8 +247,9 @@
 omitted.
 
 Normally, files are opened in :dfn:`text mode`, that means, you read and write
-strings from and to the file, which are encoded in a specific encoding (the
-default being UTF-8).  ``'b'`` appended to the mode opens the file in
+strings from and to the file, which are encoded in a specific encoding. If
+encoding is not specified, the default is platform dependent (see
+:func:`open`). ``'b'`` appended to the mode opens the file in
 :dfn:`binary mode`: now the data is read and written in the form of bytes
 objects.  This mode should be used for all files that don't contain text.
 
@@ -437,4 +438,3 @@
    written in other languages.  It is also insecure by default:
    deserializing pickle data coming from an untrusted source can execute
    arbitrary code, if the data was crafted by a skilled attacker.
-
diff --git a/Misc/NEWS b/Misc/NEWS
index 59f6af8..2c5d17a 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -51,6 +51,9 @@
 
 - Issue #23589: Remove duplicate sentence from the FAQ.  Patch by Yongzhi Pan.
 
+- Issue #24729: Correct IO tutorial to match implementation regarding
+  encoding parameter to open function.
+
 
 What's New in Python 3.5.0 beta 4?
 ==================================