python
diff --git a/‎Lib/doctest.py‎
Lines changed: 2 additions & 1 deletion b/‎Lib/doctest.py‎
Lines changed: 2 additions & 1 deletion
diff --git a/‎Misc/ACKS‎
Lines changed: 1 addition & 0 deletions b/‎Misc/ACKS‎
Lines changed: 1 addition & 0 deletions
diff --git a/‎Misc/NEWS.d/next/Library/2023-03-23-19-47-05.gh-issue-102967.gfIYkN.rst‎
Lines changed: 2 additions & 0 deletions b/‎Misc/NEWS.d/next/Library/2023-03-23-19-47-05.gh-issue-102967.gfIYkN.rst‎
Lines changed: 2 additions & 0 deletions
@@ -285,7 +285,8 @@ def getvalue(self):
         return result
 
     def truncate(self, size=None):
-        self.seek(size)
+        if size is not None:
+            self.seek(size)
         StringIO.truncate(self)
 
 # Worst-case linear-time ellipsis matching.
 
@@ -426,6 +426,7 @@ Hauke Dämpfling
 Evan Dandrea
 Eric Daniel
 Scott David Daniels
+Aaron Davidson
 Derzsi Dániel
 Lawrence D'Anna
 Steven D'Aprano
 
@@ -0,0 +1,2 @@
+A bug in :func:`!doctest._SpoofOut.truncate` was causing None to be passed to :func:`!StringIO.seek` when no size was given.
+A simple fix skips the seek call when no size is given so the buffer can be truncated from the current position.
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	+A bug in :func:`!doctest._SpoofOut.truncate` was causing None to be passed to :func:`!StringIO.seek` when no size was given.
	`2`	`+A simple fix skips the seek call when no size is given so the buffer can be truncated from the current position.`