diff --git a/runtime/doc/undo.txt b/runtime/doc/undo.txt
index 4b4104e..b806a31 100644
--- a/runtime/doc/undo.txt
+++ b/runtime/doc/undo.txt
@@ -1,4 +1,4 @@
-*undo.txt*      For Vim version 7.3.  Last change: 2010 Sep 30
+*undo.txt*      For Vim version 7.3.  Last change: 2010 Oct 21
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -239,7 +239,9 @@
 a simple scheme that maps filesystem paths directly to undo files. Vim will
 detect if an undo file is no longer synchronized with the file it was written
 for (with a hash of the file contents) and ignore it when the file was changed
-after the undo file was written, to prevent corruption.
+after the undo file was written, to prevent corruption.  An undo file is also
+ignored if its owner differs from the owner of the edited file.  Set 'verbose'
+to get a message about that.
 
 Undo files are normally saved in the same directory as the file.  This can be
 changed with the 'undodir' option.