diff --git a/src/testdir/test_maparg.vim b/src/testdir/test_maparg.vim
index ea921d6..285474d 100644
--- a/src/testdir/test_maparg.vim
+++ b/src/testdir/test_maparg.vim
@@ -238,6 +238,8 @@
   iunmap K
   let &cpo = cpo_save
   bwipe!
+
+  call assert_fails('call mapset([], v:false, {})', 'E730:')
 endfunc
 
 func Check_ctrlb_map(d, check_alt)