diff --git a/src/testdir/test_bufline.vim b/src/testdir/test_bufline.vim
index 50f7275..3c3c89c 100644
--- a/src/testdir/test_bufline.vim
+++ b/src/testdir/test_bufline.vim
@@ -20,7 +20,7 @@
   let b = bufnr('%')
   wincmd w
   call assert_equal(1, setbufline(b, 5, ['x']))
-  call assert_equal(1, setbufline(bufnr('$') + 1, 1, ['x']))
+  call assert_equal(1, ['x']->setbufline(bufnr('$') + 1, 1))
   call assert_equal(0, setbufline(b, 4, ['d', 'e']))
   call assert_equal(['c'], b->getbufline(3))
   call assert_equal(['d'], getbufline(b, 4))