diff --git a/autoload/ale/completion.vim b/autoload/ale/completion.vim
index 332d0734..4cf3a51a 100644
--- a/autoload/ale/completion.vim
+++ b/autoload/ale/completion.vim
@@ -269,13 +269,19 @@ function! s:ReplaceCompletionOptions(source) abort
             let b:ale_old_completeopt = &l:completeopt
         endif
 
-        if &l:completeopt =~# 'preview'
-            let &l:completeopt = 'menu,menuone,preview,noselect,noinsert'
-        elseif &l:completeopt =~# 'popup'
-            let &l:completeopt = 'menu,menuone,popup,noselect,noinsert'
-        else
-            let &l:completeopt = 'menu,menuone,noselect,noinsert'
-        endif
+        let l:opt_list = split(&l:completeopt, ',')
+        " The menu and noinsert options must be set, or automatic completion
+        " will be annoying.
+        let l:new_opt_list = ['menu', 'menuone', 'noinsert']
+
+        " Permit some other completion options, provided users have set them.
+        for l:opt in ['preview', 'popup', 'noselect']
+            if index(l:opt_list, l:opt) >= 0
+                call add(l:new_opt_list, l:opt)
+            endif
+        endfor
+
+        let &l:completeopt = join(l:new_opt_list, ',')
     endif
 endfunction
 
diff --git a/doc/ale.txt b/doc/ale.txt
index 9ff05059..62881503 100644
--- a/doc/ale.txt
+++ b/doc/ale.txt
@@ -561,7 +561,6 @@ vimrc, and your issues should go away. >
 
   set completeopt=menu,menuone,preview,noselect,noinsert
 <
-
 Or alternatively, if you want to show documentation in popups: >
 
   set completeopt=menu,menuone,popup,noselect,noinsert
diff --git a/test/completion/test_completion_events.vader b/test/completion/test_completion_events.vader
index 1b760e2c..ed6dbea3 100644
--- a/test/completion/test_completion_events.vader
+++ b/test/completion/test_completion_events.vader
@@ -172,7 +172,7 @@ Execute(ale#completion#Show() should remember the completeopt setting and replac
   call ale#completion#Show([{'word': 'x', 'kind': 'v', 'icase': 1}])
 
   AssertEqual 'menu', b:ale_old_completeopt
-  AssertEqual 'menu,menuone,noselect,noinsert', &l:completeopt
+  AssertEqual 'menu,menuone,noinsert', &l:completeopt
 
   AssertEqual [], g:feedkeys_calls
   sleep 1ms
@@ -185,7 +185,7 @@ Execute(ale#completion#Show() should set the preview option if it's set):
   call ale#completion#Show([{'word': 'x', 'kind': 'v', 'icase': 1}])
 
   AssertEqual 'menu,preview', b:ale_old_completeopt
-  AssertEqual 'menu,menuone,preview,noselect,noinsert', &l:completeopt
+  AssertEqual 'menu,menuone,noinsert,preview', &l:completeopt
 
   AssertEqual [], g:feedkeys_calls
   sleep 1ms
@@ -205,13 +205,13 @@ Execute(ale#completion#Show() should not replace the completeopt setting for man
   AssertEqual [["\<Plug>(ale_show_completion_menu)"]], g:feedkeys_calls
 
 Execute(ale#completion#AutomaticOmniFunc() should also remember the completeopt setting and replace it):
-  let &l:completeopt = 'menu'
+  let &l:completeopt = 'menu,noselect'
 
   let b:ale_completion_info = {'source': 'ale-automatic'}
   call ale#completion#AutomaticOmniFunc(0, '')
 
-  AssertEqual 'menu', b:ale_old_completeopt
-  AssertEqual 'menu,menuone,noselect,noinsert', &l:completeopt
+  AssertEqual 'menu,noselect', b:ale_old_completeopt
+  AssertEqual 'menu,menuone,noinsert,noselect', &l:completeopt
 
 Execute(ale#completion#AutomaticOmniFunc() should set the preview option if it's set):
   let &l:completeopt = 'menu,preview'
@@ -220,7 +220,7 @@ Execute(ale#completion#AutomaticOmniFunc() should set the preview option if it's
   call ale#completion#AutomaticOmniFunc(0, '')
 
   AssertEqual 'menu,preview', b:ale_old_completeopt
-  AssertEqual 'menu,menuone,preview,noselect,noinsert', &l:completeopt
+  AssertEqual 'menu,menuone,noinsert,preview', &l:completeopt
 
 Execute(ale#completion#Show() should make the correct feedkeys() call for automatic completion):
   let b:ale_completion_info = {'source': 'ale-automatic'}