diff --git a/src/testdir/test_packadd.vim b/src/testdir/test_packadd.vim
index 64bd8d2..f511a4d 100644
--- a/src/testdir/test_packadd.vim
+++ b/src/testdir/test_packadd.vim
@@ -12,6 +12,11 @@
 endfunc
 
 func Test_packadd()
+  if !exists('s:plugdir')
+    echomsg 'when running this test manually, call SetUp() first'
+    return
+  endif
+
   call mkdir(s:plugdir . '/plugin/also', 'p')
   call mkdir(s:plugdir . '/ftdetect', 'p')
   call mkdir(s:plugdir . '/after', 'p')
@@ -19,6 +24,14 @@
   let rtp = &rtp
   filetype on
 
+  let rtp_entries = split(rtp, ',')
+  for entry in rtp_entries
+    if entry =~? '\<after\>' 
+      let first_after_entry = entry
+      break
+    endif
+  endfor
+
   exe 'split ' . s:plugdir . '/plugin/test.vim'
   call setline(1, 'let g:plugin_works = 42')
   wq
@@ -38,7 +51,12 @@
   call assert_equal(17, g:ftdetect_works)
   call assert_true(len(&rtp) > len(rtp))
   call assert_match('/testdir/Xdir/pack/mine/opt/mytest\($\|,\)', &rtp)
-  call assert_match('/testdir/Xdir/pack/mine/opt/mytest/after$', &rtp)
+
+  let new_after = match(&rtp, '/testdir/Xdir/pack/mine/opt/mytest/after,')
+  let old_after = match(&rtp, ',' . first_after_entry . '\>')
+  call assert_true(new_after > 0, 'rtp is ' . &rtp)
+  call assert_true(old_after > 0, 'rtp is ' . &rtp)
+  call assert_true(new_after < old_after, 'rtp is ' . &rtp)
 
   " NOTE: '/.../opt/myte' forwardly matches with '/.../opt/mytest'
   call mkdir(fnamemodify(s:plugdir, ':h') . '/myte', 'p')