diff --git a/wp-admin/includes/ms.php b/wp-admin/includes/ms.php
index 787cb4532..80e2c0562 100644
--- a/wp-admin/includes/ms.php
+++ b/wp-admin/includes/ms.php
@@ -75,7 +75,7 @@ function wpmu_delete_blog($blog_id, $drop = false) {
 			$wpdb->query( "DROP TABLE IF EXISTS ". current( $drop_table ) ."" );
 		}
 		$wpdb->query( $wpdb->prepare("DELETE FROM $wpdb->blogs WHERE blog_id = %d", $blog_id) );
-		$dir = apply_filters( 'wpmu_delete_blog_upload_dir', constant( "WP_CONTENT_DIR" ) . "/blogs.dir/{$blog_id}/files/", $blog_id );
+		$dir = apply_filters( 'wpmu_delete_blog_upload_dir', WP_CONTENT_DIR . "/blogs.dir/{$blog_id}/files/", $blog_id );
 		$dir = rtrim($dir, DIRECTORY_SEPARATOR);
 		$top_dir = $dir;
 		$stack = array($dir);
diff --git a/wp-admin/includes/upgrade.php b/wp-admin/includes/upgrade.php
index f05e5982d..811d1be66 100644
--- a/wp-admin/includes/upgrade.php
+++ b/wp-admin/includes/upgrade.php
@@ -1259,11 +1259,11 @@ function __get_option($setting) {
 	global $wpdb;
 
 	if ( $setting == 'home' && defined( 'WP_HOME' ) ) {
-		return preg_replace( '|/+$|', '', constant( 'WP_HOME' ) );
+		return preg_replace( '|/+$|', '', WP_HOME );
 	}
 
 	if ( $setting == 'siteurl' && defined( 'WP_SITEURL' ) ) {
-		return preg_replace( '|/+$|', '', constant( 'WP_SITEURL' ) );
+		return preg_replace( '|/+$|', '', WP_SITEURL );
 	}
 
 	$option = $wpdb->get_var( $wpdb->prepare("SELECT option_value FROM $wpdb->options WHERE option_name = %s", $setting) );
diff --git a/wp-admin/revision.php b/wp-admin/revision.php
index 4a6e1144b..7ac404ae9 100644
--- a/wp-admin/revision.php
+++ b/wp-admin/revision.php
@@ -29,7 +29,7 @@ case 'restore' :
 	if ( !$post = get_post( $revision->post_parent ) )
 		break;
 
-	if ( !constant('WP_POST_REVISIONS') && !wp_is_post_autosave( $revision ) ) // Revisions disabled and we're not looking at an autosave
+	if ( ! WP_POST_REVISIONS && !wp_is_post_autosave( $revision ) ) // Revisions disabled and we're not looking at an autosave
 		break;
 
 	check_admin_referer( "restore-post_$post->ID|$revision->ID" );
@@ -68,7 +68,7 @@ case 'diff' :
 	else
 		break; // Don't diff two unrelated revisions
 
-	if ( !constant('WP_POST_REVISIONS') ) { // Revisions disabled
+	if ( ! WP_POST_REVISIONS ) { // Revisions disabled
 		if (
 			// we're not looking at an autosave
 			( !wp_is_post_autosave( $left_revision ) && !wp_is_post_autosave( $right_revision ) )
@@ -106,7 +106,7 @@ default :
 	if ( !current_user_can( 'read_post', $revision->ID ) || !current_user_can( 'read_post', $post->ID ) )
 		break;
 
-	if ( !constant('WP_POST_REVISIONS') && !wp_is_post_autosave( $revision ) ) // Revisions disabled and we're not looking at an autosave
+	if ( ! WP_POST_REVISIONS && !wp_is_post_autosave( $revision ) ) // Revisions disabled and we're not looking at an autosave
 		break;
 
 	$post_type_object = get_post_type_object($post->post_type);
@@ -207,7 +207,7 @@ endif;
 <?php
 
 $args = array( 'format' => 'form-table', 'parent' => true, 'right' => $right, 'left' => $left );
-if ( !constant( 'WP_POST_REVISIONS' ) )
+if ( ! WP_POST_REVISIONS )
 	$args['type'] = 'autosave';
 
 wp_list_post_revisions( $post, $args );
diff --git a/wp-includes/ms-functions.php b/wp-includes/ms-functions.php
index ecc61f00f..38f292208 100644
--- a/wp-includes/ms-functions.php
+++ b/wp-includes/ms-functions.php
@@ -1274,8 +1274,7 @@ function signup_nonce_check( $result ) {
 
 function maybe_redirect_404() {
 	global $current_site;
-	if ( is_main_site() && is_404() && defined( 'NOBLOGREDIRECT' ) && constant( 'NOBLOGREDIRECT' ) != '' ) {
-		$destination = constant( 'NOBLOGREDIRECT' );
+	if ( is_main_site() && is_404() && defined( 'NOBLOGREDIRECT' ) && ( $destination = NOBLOGREDIRECT ) ) {
 		if ( $destination == '%siteurl%' )
 			$destination = $current_site->domain . $current_site->path;
 		wp_redirect( $destination );
diff --git a/wp-includes/ms-load.php b/wp-includes/ms-load.php
index 77ba711b2..998013453 100644
--- a/wp-includes/ms-load.php
+++ b/wp-includes/ms-load.php
@@ -98,7 +98,7 @@ function get_current_site_name( $current_site ) {
 function wpmu_current_site() {
 	global $wpdb, $current_site, $domain, $path, $sites, $cookie_domain;
 	if ( defined( 'DOMAIN_CURRENT_SITE' ) && defined( 'PATH_CURRENT_SITE' ) ) {
-		$current_site->id = (defined( 'SITE_ID_CURRENT_SITE' ) ? constant('SITE_ID_CURRENT_SITE') : 1);
+		$current_site->id = defined( 'SITE_ID_CURRENT_SITE' ) ? SITE_ID_CURRENT_SITE : 1;
 		$current_site->domain = DOMAIN_CURRENT_SITE;
 		$current_site->path   = $path = PATH_CURRENT_SITE;
 		if ( defined( 'BLOGID_CURRENT_SITE' ) )
diff --git a/wp-includes/post.php b/wp-includes/post.php
index af4b12eaa..6429f9f5e 100644
--- a/wp-includes/post.php
+++ b/wp-includes/post.php
@@ -4169,7 +4169,7 @@ function wp_save_post_revision( $post_id ) {
 		return;
 
 	// WP_POST_REVISIONS = 0, false
-	if ( !constant('WP_POST_REVISIONS') )
+	if ( ! WP_POST_REVISIONS )
 		return;
 
 	if ( !$post = get_post( $post_id, ARRAY_A ) )
@@ -4448,7 +4448,7 @@ function wp_delete_post_revision( $revision_id ) {
  * @return array empty if no revisions
  */
 function wp_get_post_revisions( $post_id = 0, $args = null ) {
-	if ( !constant('WP_POST_REVISIONS') )
+	if ( ! WP_POST_REVISIONS )
 		return array();
 	if ( ( !$post = get_post( $post_id ) ) || empty( $post->ID ) )
 		return array();
diff --git a/wp-includes/template-loader.php b/wp-includes/template-loader.php
index 9fd4ffe51..6185ca93c 100644
--- a/wp-includes/template-loader.php
+++ b/wp-includes/template-loader.php
@@ -3,7 +3,7 @@
  * Loads the correct template based on the visitor's url
  * @package WordPress
  */
-if ( defined('WP_USE_THEMES') && constant('WP_USE_THEMES') ) {
+if ( defined('WP_USE_THEMES') && WP_USE_THEMES ) {
 	do_action('template_redirect');
 	if ( is_robots() ) {
 		do_action('do_robots');
diff --git a/wp-includes/wp-db.php b/wp-includes/wp-db.php
index 92df1cd5d..4422292b6 100644
--- a/wp-includes/wp-db.php
+++ b/wp-includes/wp-db.php
@@ -345,7 +345,7 @@ class wpdb {
 	 * @param string $dbhost MySQL database host
 	 */
 	function wpdb($dbuser, $dbpassword, $dbname, $dbhost) {
-		if( defined( "WP_USE_MULTIPLE_DB" ) && CONSTANT( "WP_USE_MULTIPLE_DB" ) == true )
+		if( defined( 'WP_USE_MULTIPLE_DB' ) && WP_USE_MULTIPLE_DB )
 			$this->db_connect();
 		return $this->__construct($dbuser, $dbpassword, $dbname, $dbhost);
 	}
@@ -367,23 +367,22 @@ class wpdb {
 	function __construct($dbuser, $dbpassword, $dbname, $dbhost) {
 		register_shutdown_function(array(&$this, "__destruct"));
 
-		if ( defined( 'WP_DEBUG' ) && WP_DEBUG )
+		if ( WP_DEBUG )
 			$this->show_errors();
 
 		if ( is_multisite() ) {
 			$this->charset = 'utf8';
-			if ( defined( 'DB_COLLATE' ) && constant( 'DB_COLLATE' ) != '' )
-				$this->collate = constant( 'DB_COLLATE' );
+			if ( defined( 'DB_COLLATE' ) && DB_COLLATE )
+				$this->collate = DB_COLLATE;
 			else
 				$this->collate = 'utf8_general_ci';
+		} elseif ( defined( 'DB_COLLATE' ) ) {
+			$this->collate = DB_COLLATE;
 		}
 
 		if ( defined('DB_CHARSET') )
 			$this->charset = DB_CHARSET;
 
-		if ( defined('DB_COLLATE') )
-			$this->collate = DB_COLLATE;
-
 		$this->dbuser = $dbuser;
 
 		$this->dbh = @mysql_connect($dbhost, $dbuser, $dbpassword, true);
@@ -666,7 +665,7 @@ class wpdb {
 		if ( is_multisite() ) {
 			$msg = "WordPress database error: [$str]\n{$this->last_query}\n";
 			if ( defined( 'ERRORLOGFILE' ) )
-				error_log( $msg, 3, CONSTANT( 'ERRORLOGFILE' ) );
+				error_log( $msg, 3, ERRORLOGFILE );
 			if ( defined( 'DIEONDBERROR' ) )
 				die( $msg );
 		} else {
@@ -807,7 +806,7 @@ class wpdb {
 		// use $this->dbh for read ops, and $this->dbhwrite for write ops
 		// use $this->dbhglobal for gloal table ops
 		unset( $dbh );
-		if( defined( "WP_USE_MULTIPLE_DB" ) && CONSTANT( "WP_USE_MULTIPLE_DB" ) == true ) {
+		if( defined( 'WP_USE_MULTIPLE_DB' ) && WP_USE_MULTIPLE_DB ) {
 			if( $this->blogs != '' && preg_match("/(" . $this->blogs . "|" . $this->users . "|" . $this->usermeta . "|" . $this->site . "|" . $this->sitemeta . "|" . $this->sitecategories . ")/i",$query) ) {
 				if( false == isset( $this->dbhglobal ) ) {
 					$this->db_connect( $query );