diff --git a/src/testdir/shared.vim b/src/testdir/shared.vim
index e442a59..60636fd 100644
--- a/src/testdir/shared.vim
+++ b/src/testdir/shared.vim
@@ -276,6 +276,7 @@
     let cmd = cmd . ' -u ' . name
   endif
   let cmd .= ' --not-a-term'
+  let cmd .= ' --gui-dialog-file guidialogfile'
   let cmd = substitute(cmd, 'VIMRUNTIME=\S\+', '', '')
 
   " If using valgrind, make sure every run uses a different log file.