diff --git a/Doc/library/smtplib.rst b/Doc/library/smtplib.rst
index 04036dce4c0..5762bb609f4 100644
--- a/Doc/library/smtplib.rst
+++ b/Doc/library/smtplib.rst
@@ -103,7 +103,7 @@ A nice selection of exceptions is defined as well:
 
 .. exception:: SMTPException
 
-   Subclass of :exc:`IOError` that is the base exception class for all
+   Subclass of :exc:`OSError` that is the base exception class for all
    the other excpetions provided by this module.
 
 
diff --git a/Doc/whatsnew/3.4.rst b/Doc/whatsnew/3.4.rst
index 2b6193a2152..ca515f6c82a 100644
--- a/Doc/whatsnew/3.4.rst
+++ b/Doc/whatsnew/3.4.rst
@@ -162,7 +162,7 @@ detected.  (Contributed by R. David Murray and Daniel Urban in :issue:`16522`.)
 smtplib
 -------
 
-:exc:`~smtplib.SMTPException` is now a subclass of :exc:`IOError`, which allows
+:exc:`~smtplib.SMTPException` is now a subclass of :exc:`OSError`, which allows
 both socket level errors and SMTP protocol level errors to be caught in one
 try/except statement by code that only cares whether or not an error occurred.
 (:issue:`2118`).
diff --git a/Lib/smtplib.py b/Lib/smtplib.py
index a5a9fd4c8de..cc46e4f49f5 100644
--- a/Lib/smtplib.py
+++ b/Lib/smtplib.py
@@ -66,7 +66,7 @@
 OLDSTYLE_AUTH = re.compile(r"auth=(.*)", re.I)
 
 # Exception classes used by this module.
-class SMTPException(IOError):
+class SMTPException(OSError):
     """Base class for all exceptions raised by this module."""
 
 class SMTPServerDisconnected(SMTPException):