diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index 85e27c6..938a839 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -950,6 +950,8 @@
 
   " Using $ instead of '$' must give an error
   call assert_fails("call append($, 'foobar')", 'E116:')
+
+  call assert_fails("call append({}, '')", ['E728:', 'E728:'])
 endfunc
 
 " Test for setline()