diff --git a/src/testdir/test_undo.vim b/src/testdir/test_undo.vim
index 844ba77..af6cefe 100644
--- a/src/testdir/test_undo.vim
+++ b/src/testdir/test_undo.vim
@@ -849,6 +849,7 @@
 endfunc
 
 func Test_undo_after_write()
+  CheckScreendump
   " use a terminal to make undo work like when text is typed
   CheckRunVimInTerminal