diff --git a/autoload/airline/extensions.vim b/autoload/airline/extensions.vim
index 891007d..9efa679 100644
--- a/autoload/airline/extensions.vim
+++ b/autoload/airline/extensions.vim
@@ -18,11 +18,6 @@ function! airline#extensions#apply_left_override(section1, section2)
   let w:airline_left_only = 1
 endfunction
 
-function! airline#extensions#update_external_values()
-  let g:airline_externals_tagbar = g:airline_enable_tagbar && exists(':Tagbar')
-        \ ? '%(%{tagbar#currenttag("%s","")} '.g:airline_right_alt_sep.' %)' : ''
-endfunction
-
 function! airline#extensions#apply_window_overrides()
   if &buftype == 'quickfix'
     let w:airline_section_a = 'Quickfix'
@@ -114,6 +109,10 @@ function! airline#extensions#load()
     call airline#extensions#commandt#init(s:ext)
   endif
 
+  if get(g:, 'loaded_tagbar', 0)
+    call airline#extensions#tagbar#init(s:ext)
+  endif
+
   if g:airline_enable_branch && (get(g:, 'loaded_fugitive', 0) || get(g:, 'loaded_lawrencium', 0))
     call airline#extensions#branch#init(s:ext)
   endif
@@ -126,7 +125,6 @@ function! airline#extensions#load()
     call airline#extensions#bufferline#init(s:ext)
   endif
 
-  call add(g:airline_statusline_funcrefs, function('airline#extensions#update_external_values'))
   call add(g:airline_statusline_funcrefs, function('airline#extensions#apply_window_overrides'))
   call add(g:airline_exclude_funcrefs, function('airline#extensions#is_excluded_window'))
 
diff --git a/autoload/airline/extensions/tagbar.vim b/autoload/airline/extensions/tagbar.vim
new file mode 100644
index 0000000..8131652
--- /dev/null
+++ b/autoload/airline/extensions/tagbar.vim
@@ -0,0 +1,11 @@
+" MIT license. Copyright (c) 2013 Bailey Ling.
+" vim: ts=2 sts=2 sw=2 fdm=indent
+
+function! airline#extensions#tagbar#apply()
+  let w:airline_section_x = '%(%{tagbar#currenttag("%s","")} '.g:airline_right_alt_sep.' %)'.g:airline_section_x
+endfunction
+
+function! airline#extensions#tagbar#init(ext)
+  call a:ext.add_statusline_funcref(function('airline#extensions#tagbar#apply'))
+endfunction
+
diff --git a/plugin/airline.vim b/plugin/airline.vim
index 745f214..e637ce6 100644
--- a/plugin/airline.vim
+++ b/plugin/airline.vim
@@ -48,6 +48,14 @@ call s:check_defined('g:airline_mode_map', {
       \ '' : 'V-BLOCK',
       \ })
 
+call s:check_defined('g:airline_section_a', '%{g:airline_current_mode_text}')
+call s:check_defined('g:airline_section_b', '')
+call s:check_defined('g:airline_section_c', '%f%m')
+call s:check_defined('g:airline_section_gutter', '')
+call s:check_defined('g:airline_section_x', "%{strlen(&filetype)>0?&filetype:''}")
+call s:check_defined('g:airline_section_y', "%{strlen(&fenc)>0?&fenc:''}%{strlen(&ff)>0?'['.&ff.']':''}")
+call s:check_defined('g:airline_section_z', '%3p%% '.g:airline_linecolumn_prefix.'%3l:%3c')
+
 let s:airline_initialized = 0
 let s:active_winnr = -1
 function! s:on_window_changed()
@@ -55,13 +63,6 @@ function! s:on_window_changed()
   if !s:airline_initialized
     call airline#extensions#load()
     call airline#load_theme(g:airline_theme)
-    call s:check_defined('g:airline_section_a', '%{g:airline_current_mode_text}')
-    call s:check_defined('g:airline_section_b', '')
-    call s:check_defined('g:airline_section_c', '%f%m')
-    call s:check_defined('g:airline_section_gutter', '')
-    call s:check_defined('g:airline_section_x', g:airline_externals_tagbar."%{strlen(&filetype)>0?&filetype:''}")
-    call s:check_defined('g:airline_section_y', "%{strlen(&fenc)>0?&fenc:''}%{strlen(&ff)>0?'['.&ff.']':''}")
-    call s:check_defined('g:airline_section_z', '%3p%% '.g:airline_linecolumn_prefix.'%3l:%3c')
     let s:airline_initialized = 1
   endif
   call airline#update_statusline()