diff --git a/autoload/airline.vim b/autoload/airline.vim
index 77de75e3..1ce78d56 100644
--- a/autoload/airline.vim
+++ b/autoload/airline.vim
@@ -13,61 +13,6 @@ let s:airline_highlight_map = {
       \ 'file'           : 'Al7',
       \ }
 
-function! s:create_builder(active)
-  let builder = {}
-  let builder._sections = []
-  let builder._active = a:active
-
-  function! builder.split(gutter)
-    call add(self._sections, ['|', a:gutter])
-  endfunction
-
-  function! builder.add_section(group, contents)
-    call add(self._sections, [a:group, a:contents])
-  endfunction
-
-  function! builder.add_raw(text)
-    call add(self._sections, ['_', a:text])
-  endfunction
-
-  function! builder._group(group)
-    return '%#' . (self._active ? a:group : a:group.'_inactive') . '#'
-  endfunction
-
-  function! builder.build()
-    let line = '%{airline#update_highlight()}'
-    let side = 0
-    let prev_group = ''
-    for section in self._sections
-      if section[0] == '|'
-        let side = 1
-        let line .= '%#'.prev_group.'#'.section[1]
-        let prev_group = ''
-        continue
-      endif
-      if section[0] == '_'
-        let line .= section[1]
-        continue
-      endif
-
-      if prev_group != ''
-        let line .= side == 0
-              \ ? self._group(airline#themes#exec_highlight_separator(section[0], prev_group))
-              \ : self._group(airline#themes#exec_highlight_separator(prev_group, section[0]))
-        let line .= side == 0
-              \ ? self._active ? g:airline_left_sep : g:airline_left_alt_sep
-              \ : self._active ? g:airline_right_sep : g:airline_right_alt_sep
-      endif
-
-      let line .= self._group(section[0]).section[1]
-      let prev_group = section[0]
-    endfor
-    return line
-  endfunction
-
-  return builder
-endfunction
-
 function! airline#exec_highlight(group, colors)
   let colors = a:colors
   if s:is_win32term
@@ -126,7 +71,7 @@ function! s:get_section(winnr, key, ...)
 endfunction
 
 function! airline#get_statusline(winnr, active)
-  let builder = s:create_builder(a:active)
+  let builder = airline#builder#new(a:active)
 
   if s:getwinvar(a:winnr, 'airline_render_left', a:active || (!a:active && !g:airline_inactive_collapse))
     call builder.add_section('Al2', s:get_section(a:winnr, 'a').'%{g:airline_detect_paste && &paste ? g:airline_paste_symbol." " : ""}')
diff --git a/autoload/airline/builder.vim b/autoload/airline/builder.vim
new file mode 100644
index 00000000..5b443dd5
--- /dev/null
+++ b/autoload/airline/builder.vim
@@ -0,0 +1,57 @@
+" MIT license. Copyright (c) 2013 Bailey Ling.
+" vim: ts=2 sts=2 sw=2 fdm=indent
+
+function! airline#builder#new(active)
+  let builder = {}
+  let builder._sections = []
+  let builder._active = a:active
+
+  function! builder.split(gutter)
+    call add(self._sections, ['|', a:gutter])
+  endfunction
+
+  function! builder.add_section(group, contents)
+    call add(self._sections, [a:group, a:contents])
+  endfunction
+
+  function! builder.add_raw(text)
+    call add(self._sections, ['_', a:text])
+  endfunction
+
+  function! builder._group(group)
+    return '%#' . (self._active ? a:group : a:group.'_inactive') . '#'
+  endfunction
+
+  function! builder.build()
+    let line = '%{airline#update_highlight()}'
+    let side = 0
+    let prev_group = ''
+    for section in self._sections
+      if section[0] == '|'
+        let side = 1
+        let line .= '%#'.prev_group.'#'.section[1]
+        let prev_group = ''
+        continue
+      endif
+      if section[0] == '_'
+        let line .= section[1]
+        continue
+      endif
+
+      if prev_group != ''
+        let line .= side == 0
+              \ ? self._group(airline#themes#exec_highlight_separator(section[0], prev_group))
+              \ : self._group(airline#themes#exec_highlight_separator(prev_group, section[0]))
+        let line .= side == 0
+              \ ? self._active ? g:airline_left_sep : g:airline_left_alt_sep
+              \ : self._active ? g:airline_right_sep : g:airline_right_alt_sep
+      endif
+
+      let line .= self._group(section[0]).section[1]
+      let prev_group = section[0]
+    endfor
+    return line
+  endfunction
+
+  return builder
+endfunction