diff --git a/wp-admin/admin-functions.php b/wp-admin/admin-functions.php
index 2b5e6a6091..9c065765e2 100644
--- a/wp-admin/admin-functions.php
+++ b/wp-admin/admin-functions.php
@@ -1721,8 +1721,7 @@ function get_plugins() {
 	}
 
 	$wp_plugins = array ();
-	$plugin_loc = 'wp-content/plugins';
-	$plugin_root = ABSPATH.$plugin_loc;
+	$plugin_root = ABSPATH . PLUGINDIR;
 
 	// Files in wp-content/plugins directory
 	$plugins_dir = @ dir($plugin_root);
diff --git a/wp-admin/admin.php b/wp-admin/admin.php
index 8e3a45fea3..3c2afcff62 100644
--- a/wp-admin/admin.php
+++ b/wp-admin/admin.php
@@ -52,7 +52,7 @@ if (isset($plugin_page)) {
 			wp_die(__('Invalid plugin page'));
 		}
 
-		if (! file_exists(ABSPATH . "wp-content/plugins/$plugin_page"))
+		if (! file_exists(ABSPATH . PLUGINDIR . "/$plugin_page"))
 			wp_die(sprintf(__('Cannot load %s.'), htmlentities($plugin_page)));
 
 		do_action('load-' . $plugin_page);
@@ -60,7 +60,7 @@ if (isset($plugin_page)) {
 		if (! isset($_GET['noheader']))
 			require_once(ABSPATH . '/wp-admin/admin-header.php');
 
-		include(ABSPATH . "wp-content/plugins/$plugin_page");
+		include(ABSPATH . PLUGINDIR . "/$plugin_page");
 	}
 
 	include(ABSPATH . 'wp-admin/admin-footer.php');
diff --git a/wp-admin/menu-header.php b/wp-admin/menu-header.php
index 417a84fbd2..99c02a5966 100644
--- a/wp-admin/menu-header.php
+++ b/wp-admin/menu-header.php
@@ -12,7 +12,7 @@ foreach ($menu as $item) {
 	if (( strcmp($self, $item[2]) == 0 && empty($parent_file)) || ($parent_file && ($item[2] == $parent_file))) $class = ' class="current"';
     
 	if ( !empty($submenu[$item[2]]) || current_user_can($item[1]) ) {
-		if ( file_exists(ABSPATH . "wp-content/plugins/{$item[2]}") )
+		if ( file_exists(ABSPATH . PLUGINDIR . "/{$item[2]}") )
 			echo "\n\t<li><a href='" . get_option('siteurl') . "/wp-admin/admin.php?page={$item[2]}'$class>{$item[0]}</a></li>";
 		else
 			echo "\n\t<li><a href='" . get_option('siteurl') . "/wp-admin/{$item[2]}'$class>{$item[0]}</a></li>";
@@ -40,7 +40,7 @@ else $class = '';
 
 $menu_hook = get_plugin_page_hook($item[2], $parent_file);
 
-if (file_exists(ABSPATH . "wp-content/plugins/{$item[2]}") || ! empty($menu_hook)) {
+if (file_exists(ABSPATH . PLUGINDIR . "/{$item[2]}") || ! empty($menu_hook)) {
  	if ( 'admin.php' == $pagenow )
 		echo "\n\t<li><a href='" . get_option('siteurl') . "/wp-admin/admin.php?page={$item[2]}'$class>{$item[0]}</a></li>";
 	else
@@ -58,4 +58,4 @@ endif;
 
 do_action('admin_notices');
 
-?>
\ No newline at end of file
+?>
diff --git a/wp-admin/plugin-editor.php b/wp-admin/plugin-editor.php
index f27e312187..9d311d924b 100644
--- a/wp-admin/plugin-editor.php
+++ b/wp-admin/plugin-editor.php
@@ -14,7 +14,7 @@ if (empty($file)) {
 }
 
 $file = validate_file_to_edit($file, $plugin_files);
-$real_file = get_real_file_to_edit("wp-content/plugins/$file");
+$real_file = get_real_file_to_edit( PLUGINDIR . "/$file");
 
 switch($action) {
 
@@ -46,7 +46,7 @@ default:
 
 	require_once('admin-header.php');
 
-	update_recently_edited("wp-content/plugins/$file");
+	update_recently_edited(PLUGINDIR . "/$file");
 
 	if (!is_file($real_file))
 		$error = 1;
diff --git a/wp-admin/plugins.php b/wp-admin/plugins.php
index 6fbc814950..3fa7c02c73 100644
--- a/wp-admin/plugins.php
+++ b/wp-admin/plugins.php
@@ -9,7 +9,7 @@ if ( isset($_GET['action']) ) {
 			$current[] = trim( $_GET['plugin'] );
 			sort($current);
 			update_option('active_plugins', $current);
-			include(ABSPATH . 'wp-content/plugins/' . trim( $_GET['plugin'] ));
+			include(ABSPATH . PLUGINDIR . '/' . trim( $_GET['plugin'] ));
 			do_action('activate_' . trim( $_GET['plugin'] ));
 		}
 		wp_redirect('plugins.php?activate=true');
@@ -42,7 +42,7 @@ if ( !is_array($check_plugins) ) {
 // If a plugin file does not exist, remove it from the list of active
 // plugins.
 foreach ($check_plugins as $check_plugin) {
-	if (!file_exists(ABSPATH . 'wp-content/plugins/' . $check_plugin)) {
+	if (!file_exists(ABSPATH . PLUGINDIR . '/' . $check_plugin)) {
 			$current = get_option('active_plugins');
 			$key = array_search($check_plugin, $current);
 			if ( false !== $key && NULL !== $key ) {
@@ -123,10 +123,10 @@ if (empty($plugins)) {
 }
 ?>
 
-<p><?php _e('If something goes wrong with a plugin and you can&#8217;t use WordPress, delete or rename that file in the <code>wp-content/plugins</code> directory and it will be automatically deactivated.'); ?></p>
+<p><?php _e(sprintf('If something goes wrong with a plugin and you can&#8217;t use WordPress, delete or rename that file in the <code>%s</code> directory and it will be automatically deactivated.', PLUGINDIR)); ?></p>
 
 <h2><?php _e('Get More Plugins'); ?></h2>
-<p><?php _e('You can find additional plugins for your site in the <a href="http://wordpress.org/extend/plugins/">WordPress plugin directory</a>. To install a plugin you generally just need to upload the plugin file into your <code>wp-content/plugins</code> directory. Once a plugin is uploaded, you may activate it here.'); ?></p>
+<p><?php _e(sprintf('You can find additional plugins for your site in the <a href="http://wordpress.org/extend/plugins/">WordPress plugin directory</a>. To install a plugin you generally just need to upload the plugin file into your <code>%s</code> directory. Once a plugin is uploaded, you may activate it here.', PLUGINDIR)); ?></p>
 
 </div>
 
diff --git a/wp-includes/l10n.php b/wp-includes/l10n.php
index ba77c2359e..b2b099c422 100644
--- a/wp-includes/l10n.php
+++ b/wp-includes/l10n.php
@@ -1,10 +1,4 @@
 <?php
-
-if ( defined('WPLANG') && '' != constant('WPLANG') ) {
-	include_once(ABSPATH . 'wp-includes/streams.php');
-	include_once(ABSPATH . 'wp-includes/gettext.php');
-}
-
 function get_locale() {
 	global $locale;
 
@@ -75,13 +69,15 @@ function load_default_textdomain() {
 	global $l10n;
 
 	$locale = get_locale();
-	$mofile = ABSPATH . "wp-includes/languages/$locale.mo";
+	$mofile = ABSPATH . LANGDIR . "/$locale.mo";
 
 	load_textdomain('default', $mofile);
 }
 
-function load_plugin_textdomain($domain, $path = 'wp-content/plugins') {
+function load_plugin_textdomain($domain, $path = false) {
 	$locale = get_locale();
+	if ( false === $path )
+		$path = PLUGINDIR;
 
 	$mofile = ABSPATH . "$path/$domain-$locale.mo";
 	load_textdomain($domain, $mofile);
@@ -94,4 +90,4 @@ function load_theme_textdomain($domain) {
 	load_textdomain($domain, $mofile);
 }
 
-?>
\ No newline at end of file
+?>
diff --git a/wp-settings.php b/wp-settings.php
index 4bbccf6cfe..f92439206d 100644
--- a/wp-settings.php
+++ b/wp-settings.php
@@ -81,6 +81,10 @@ if ( defined('WP_CACHE') )
 	require (ABSPATH . 'wp-content/advanced-cache.php');
 
 define('WPINC', 'wp-includes');
+if ( !defined('LANGDIR') )
+	define('LANGDIR', WPINC . '/languages');   // no leading slash, no trailing slash
+if ( !defined('PLUGINDIR') )
+	define('PLUGINDIR', 'wp-content/plugins'); // no leading slash, no trailing slash
 if ( file_exists(ABSPATH . 'wp-content/db.php') )
 	require (ABSPATH . 'wp-content/db.php');
 else
@@ -119,6 +123,10 @@ wp_cache_init();
 require (ABSPATH . WPINC . '/functions.php');
 require (ABSPATH . WPINC . '/plugin.php');
 require (ABSPATH . WPINC . '/default-filters.php');
+if ( defined('WPLANG') && '' != constant('WPLANG') ) {
+	include_once(ABSPATH . WPINC . '/streams.php');
+	include_once(ABSPATH . WPINC . '/gettext.php');
+}
 require_once (ABSPATH . WPINC . '/l10n.php');
 
 if ( !is_blog_installed() && (!strstr($_SERVER['PHP_SELF'], 'install.php') && !defined('WP_INSTALLING')) ) {