diff --git a/wp-admin/setup-config.php b/wp-admin/setup-config.php
index 566fd835d..86e7ceac1 100644
--- a/wp-admin/setup-config.php
+++ b/wp-admin/setup-config.php
@@ -1,5 +1,8 @@
 <?php
 define('WP_INSTALLING', true);
+//These two defines are required to allow us to use require_wp_db() to load the database class while being wp-content/wp-db.php aware
+define('ABSPATH', dirname(dirname(__FILE__)).'/');
+define('WPINC', 'wp-includes');
 
 require_once('../wp-includes/compat.php');
 require_once('../wp-includes/functions.php');
@@ -160,7 +163,7 @@ switch($step) {
 	define('DB_HOST', $dbhost);
 
 	// We'll fail here if the values are no good.
-	require_once('../wp-includes/wp-db.php');
+	require_wp_db();
 	$handle = fopen('../wp-config.php', 'w');
 
 	foreach ($configFile as $line_num => $line) {
diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index 1b4517ffb..b33905501 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -1415,4 +1415,21 @@ function wp_ob_end_flush_all()
 	while ( @ob_end_flush() );
 }
 
+/*
+ * require_wp_db() - require_once the correct database class file.
+ *
+ * This function is used to load the database class file either at runtime or by wp-admin/setup-config.php
+ * We must globalise $wpdb to ensure that it is defined globally by the inline code in wp-db.php
+ *
+ * @global $wpdb
+ */
+function require_wp_db()
+{
+	global $wpdb;
+	if ( file_exists(ABSPATH . 'wp-content/db.php') )
+		require_once (ABSPATH . 'wp-content/db.php');
+	else
+		require_once (ABSPATH . WPINC . '/wp-db.php');
+}
+
 ?>
diff --git a/wp-settings.php b/wp-settings.php
index 88146d6be..215dd6374 100644
--- a/wp-settings.php
+++ b/wp-settings.php
@@ -121,11 +121,7 @@ if ( !defined('PLUGINDIR') )
 require (ABSPATH . WPINC . '/compat.php');
 require (ABSPATH . WPINC . '/functions.php');
 
-if ( file_exists(ABSPATH . 'wp-content/db.php') )
-	require_once (ABSPATH . 'wp-content/db.php');
-else
-	require_once (ABSPATH . WPINC . '/wp-db.php');
-
+require_wp_db();
 // $table_prefix is deprecated as of 2.1
 $wpdb->prefix = $table_prefix;