diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index 8ee3679..1cce8a0 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -1497,6 +1497,7 @@
 
 func Test_balloon_show()
   CheckFeature balloon_eval
+
   " This won't do anything but must not crash either.
   call balloon_show('hi!')
   if !has('gui_running')
@@ -2650,4 +2651,12 @@
   call assert_fails('call browsedir("open", [])', 'E730:')
 endfunc
 
+func HasDefault(msg = 'msg')
+  return a:msg
+endfunc
+
+func Test_default_arg_value()
+  call assert_equal('msg', HasDefault())
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab