diff --git a/src/testdir/test_undo.vim b/src/testdir/test_undo.vim
index 06732af..e785c60 100644
--- a/src/testdir/test_undo.vim
+++ b/src/testdir/test_undo.vim
@@ -3,6 +3,7 @@
 " undo-able pieces.  Do that by setting 'undolevels'.
 " Also tests :earlier and :later.
 
+set belloff=all
 func Test_undotree()
   exe "normal Aabc\<Esc>"
   set ul=100