diff --git a/nvim/init.vim b/nvim/init.vim
index 2afa704..547f3c7 100644
--- a/nvim/init.vim
+++ b/nvim/init.vim
@@ -125,9 +125,6 @@ augroup close_preview
 	autocmd InsertLeave * silent! pclose!
 augroup end
 
-inoremap <expr> <Tab> pumvisible() ? "\<C-n>" : "\<Tab>"
-inoremap <expr> <S-Tab> pumvisible() ? "\<C-p>" : "\<S-Tab>"
-
 " autoread/checktime timer {{{
 set autoread
 function! CheckTime(timer)
@@ -174,3 +171,20 @@ nnoremap <silent> K :call CocAction('doHover')<CR>
 
 nmap <silent> gd <Plug>(coc-definition)
 nmap <silent> gr <Plug>(coc-references)
+
+" use <tab> for trigger completion and navigate to the next complete item
+function! s:check_back_space() abort
+  let col = col('.') - 1
+  return !col || getline('.')[col - 1]  =~ '\s'
+endfunction
+
+inoremap <silent><expr> <Tab>
+      \ pumvisible() ? "\<C-n>" :
+      \ <SID>check_back_space() ? "\<Tab>" :
+      \ coc#refresh()
+
+inoremap <silent><expr> <S-Tab>
+      \ pumvisible() ? "\<C-p>" :
+      \ <SID>check_back_space() ? "\<S-Tab>" :
+      \ coc#refresh()
+