diff --git a/autoload/airline/extensions/example.vim b/autoload/airline/extensions/example.vim
index d522bd6..0f571f2 100644
--- a/autoload/airline/extensions/example.vim
+++ b/autoload/airline/extensions/example.vim
@@ -11,7 +11,7 @@ function! airline#extensions#example#init(ext)
 
   " Here we define a new part for the plugin.  This allows users to place this
   " extension in arbitrary locations.
-  let g:airline_parts.cats = '%{airline#extensions#example#get_cats()}'
+  call airline#parts#define_raw('cats', '%{airline#extensions#example#get_cats()}')
 
   " Next up we add a funcref so that we can run some code prior to the
   " statusline getting modifed.
@@ -28,7 +28,7 @@ function! airline#extensions#example#apply(...)
     " Let's use a helper function.  It will take care of ensuring that the
     " window-local override exists (and create one based on the global
     " airline_section if not), and prepend to it.
-    call airline#extensions#prepend_to_section('x', g:airline_parts.cats)
+    call airline#extensions#prepend_to_section('x', airline#parts#get('cats').raw)
   endif
 endfunction
 
diff --git a/autoload/airline/extensions/syntastic.vim b/autoload/airline/extensions/syntastic.vim
index 24308c5..a91ec66 100644
--- a/autoload/airline/extensions/syntastic.vim
+++ b/autoload/airline/extensions/syntastic.vim
@@ -10,6 +10,6 @@ function! airline#extensions#syntastic#get_warnings()
 endfunction
 
 function! airline#extensions#syntastic#init(ext)
-  let g:airline_parts.syntastic = '%{airline#extensions#syntastic#get_warnings()}'
+  call airline#parts#define_function('syntastic', 'airline#extensions#syntastic#get_warnings')
 endfunction
 
diff --git a/autoload/airline/extensions/tagbar.vim b/autoload/airline/extensions/tagbar.vim
index 4b51787..214d443 100644
--- a/autoload/airline/extensions/tagbar.vim
+++ b/autoload/airline/extensions/tagbar.vim
@@ -27,6 +27,6 @@ function! airline#extensions#tagbar#init(ext)
   call a:ext.add_inactive_statusline_func('airline#extensions#tagbar#inactive_apply')
   let g:tagbar_status_func = 'airline#extensions#tagbar#get_status'
 
-  let g:airline_parts.tagbar = 'airline#extensions#tagbar#currenttag'
+  call airline#parts#define_function('tagbar', 'airline#extensions#tagbar#currenttag')
 endfunction
 
diff --git a/autoload/airline/extensions/whitespace.vim b/autoload/airline/extensions/whitespace.vim
index 0aa8fbe..234c732 100644
--- a/autoload/airline/extensions/whitespace.vim
+++ b/autoload/airline/extensions/whitespace.vim
@@ -65,7 +65,7 @@ function! airline#extensions#whitespace#toggle()
 endfunction
 
 function! airline#extensions#whitespace#init(...)
-  let g:airline_parts.whitespace = '%{airline#extensions#whitespace#check()}'
+  call airline#parts#define_function('whitespace', 'airline#extensions#whitespace#check')
 
   unlet! b:airline_whitespace_check
   augroup airline_whitespace
diff --git a/autoload/airline/init.vim b/autoload/airline/init.vim
index a08542b..80ab516 100644
--- a/autoload/airline/init.vim
+++ b/autoload/airline/init.vim
@@ -37,14 +37,7 @@ function! airline#init#bootstrap()
         \ 'highlight': 'airline_file',
         \ })
   call airline#parts#define_raw('file', '%f%m')
-
-  call s:check_defined('g:airline_parts', {})
-  call extend(g:airline_parts, {
-        \ 'ffenc': '%{printf("%s%s",&fenc,strlen(&ff)>0?"[".&ff."]":"")}',
-        \ 'tagbar': 'airline#parts#empty',
-        \ 'syntastic': 'airline#parts#empty',
-        \ 'whitespace': 'airline#parts#empty',
-        \ }, 'keep')
+  call airline#parts#define_raw('ffenc', '%{printf("%s%s",&fenc,strlen(&ff)>0?"[".&ff."]":"")}')
 
   call s:check_defined('g:airline_mode_map', {})
   call extend(g:airline_mode_map, {
diff --git a/doc/airline.txt b/doc/airline.txt
index 5bcac27..4159728 100644
--- a/doc/airline.txt
+++ b/doc/airline.txt
@@ -388,9 +388,6 @@ For contributions into the plugin, here are the following guidelines:
   b.  Configuration variables for the extension should reside in the
       extension, e.g. `g:airline#extensions#foo_plugin#bar_variable`.
 
-  c.  A value should be added to the `g:airline_parts` dictionary such that
-      the extension can be arbitrarily positioned.
-
 See the source of |example.vim| for a working extension.
 
 ==============================================================================