diff --git a/wp-blog-header.php b/wp-blog-header.php
index 411b93159e..00d3ccd5d3 100644
--- a/wp-blog-header.php
+++ b/wp-blog-header.php
@@ -7,6 +7,7 @@ if ( !file_exists( dirname(__FILE__) . '/wp-config.php') ) {
 
 	require_once( dirname(__FILE__) . '/wp-includes/classes.php');
 	require_once( dirname(__FILE__) . '/wp-includes/functions.php');
+	require_once( dirname(__FILE__) . '/wp-includes/plugin.php');
 	wp_die("There doesn't seem to be a <code>wp-config.php</code> file. I need this before we can get started. Need more help? <a href='http://codex.wordpress.org/Editing_wp-config.php'>We got it</a>. You can <a href='{$path}setup-config.php'>create a <code>wp-config.php</code> file through a web interface</a>, but this doesn't work for all server setups. The safest way is to manually create the file.", "WordPress &rsaquo; Error");
 }