diff --git a/src/testdir/test_help.vim b/src/testdir/test_help.vim
index 85c1296..c550ff0 100644
--- a/src/testdir/test_help.vim
+++ b/src/testdir/test_help.vim
@@ -30,3 +30,22 @@
   close
   bwipe!
 endfunc
+
+func Test_help_local_additions()
+  call mkdir('Xruntime/doc', 'p')
+  call writefile(['*mydoc.txt* my awesome doc'], 'Xruntime/doc/mydoc.txt')
+  call writefile(['*mydoc-ext.txt* my extended awesome doc'], 'Xruntime/doc/mydoc-ext.txt')
+  let rtp_save = &rtp
+  set rtp+=./Xruntime
+  help
+  1
+  call search('mydoc.txt')
+  call assert_equal('|mydoc.txt| my awesome doc', getline('.'))
+  1
+  call search('mydoc-ext.txt')
+  call assert_equal('|mydoc-ext.txt| my extended awesome doc', getline('.'))
+  close
+
+  call delete('Xruntime', 'rf')
+  let &rtp = rtp_save
+endfunc