diff --git a/src/testdir/test_diffmode.vim b/src/testdir/test_diffmode.vim
index 8596331..81913c8 100644
--- a/src/testdir/test_diffmode.vim
+++ b/src/testdir/test_diffmode.vim
@@ -922,6 +922,9 @@
 
   call VerifyScreenDump(buf, 'Test_diff_of_diff_01', {})
 
+  call term_sendkeys(buf, ":set rightleft\<cr>")
+  call VerifyScreenDump(buf, 'Test_diff_of_diff_02', {})
+
   " clean up
   call StopVimInTerminal(buf)
   call delete('Xtest_diff_diff')