diff --git a/autoload/lightline.vim b/autoload/lightline.vim
index edcae03..ca4c9dd 100644
--- a/autoload/lightline.vim
+++ b/autoload/lightline.vim
@@ -2,7 +2,7 @@
 " Filename: autoload/lightline.vim
 " Author: itchyny
 " License: MIT License
-" Last Change: 2018/09/16 23:00:00.
+" Last Change: 2018/09/17 12:00:00.
 " =============================================================================
 
 let s:save_cpo = &cpo
@@ -394,6 +394,11 @@ function! s:expand(components) abort
     let prevtype = type
     let previndex = index
   endfor
+  for i in range(previndex + 1, max([previndex, len(a:components) - 1]))
+    call add(indices, string(i))
+    call add(components, [])
+    call add(expanded, [])
+  endfor
   call add(indices, string(len(a:components)))
   return [components, expanded, indices]
 endfunction
diff --git a/test/expand.vim b/test/expand.vim
index 0a132e2..3bd4a6b 100644
--- a/test/expand.vim
+++ b/test/expand.vim
@@ -507,6 +507,22 @@ function! s:suite.custom_type_notfound()
         \ [[['readonly', 'filename', 'modified']], [[0, 0, 0]], ['0', '1']])
 endfunction
 
+function! s:suite.duplicated_string()
+  function! Custom()
+    return 'custom'
+  endfunction
+  function! Modified()
+    return ''
+  endfunction
+  let g:lightline = { 'component_expand': { 'custom': 'Custom', 'modified': 'Modified' } }
+  call lightline#init()
+  call s:assert.equals(s:expand([['filename'], ['custom', 'custom'], ['modified']]),
+        \ [[['filename'], ['custom', 'custom'], []], [[0], [1, 1], []], ['0', '1', '2', '3']])
+  call s:assert.equals(s:expand([['filename', 'custom', 'custom', 'modified']]),
+        \ [[['filename', 'custom', 'custom']], [[0, 1, 1]], ['0', '1']])
+  delfunction Custom
+endfunction
+
 function! s:suite.duplicated_left_nil()
   function! Custom()
     return [ [], ['y0', 'y1'], ['z0', 'z1'] ]