diff --git a/src/testdir/test_highlight.vim b/src/testdir/test_highlight.vim
index 05f215a..8bd03e2 100644
--- a/src/testdir/test_highlight.vim
+++ b/src/testdir/test_highlight.vim
@@ -808,6 +808,7 @@
   call assert_notmatch('ctermul=', HighlightArgs('Normal'))
   highlight Normal ctermul=3
   call assert_match('ctermul=3', HighlightArgs('Normal'))
+  call assert_equal('3', synIDattr(synIDtrans(hlID('Normal')), 'ul'))
   highlight Normal ctermul=NONE
 endfunc