diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index fd9057d..70dc339 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -1438,19 +1438,19 @@
   let prev_id = win_getid()
 
   wincmd j
-  let wh = winheight('.')
+  let wh = winheight(0)
   let dummy_buf = bufnr('dummy_buf1', v:true)
   call setbufvar(dummy_buf, '&buftype', 'nofile')
   execute 'belowright vertical split #' . dummy_buf
-  call assert_equal(wh, winheight('.'))
+  call assert_equal(wh, winheight(0))
   let dum1_id = win_getid()
 
   wincmd h
-  let wh = winheight('.')
+  let wh = winheight(0)
   let dummy_buf = bufnr('dummy_buf2', v:true)
   eval 'nofile'->setbufvar(dummy_buf, '&buftype')
   execute 'belowright vertical split #' . dummy_buf
-  call assert_equal(wh, winheight('.'))
+  call assert_equal(wh, winheight(0))
 
   bwipe!
   call win_gotoid(prev_id)