diff --git wp-admin/includes/class-wp-upgrader.php wp-admin/includes/class-wp-upgrader.php
index d3abd8e..4327c07 100644
--- wp-admin/includes/class-wp-upgrader.php
+++ wp-admin/includes/class-wp-upgrader.php
@@ -738,7 +738,7 @@ class WP_Upgrader {
 	 */
 	public function maintenance_mode( $enable = false ) {
 		global $wp_filesystem;
-		$file = $wp_filesystem->abspath() . '.maintenance';
+		$file = $wp_filesystem->abspath() . 'wordpress.maintenance';
 		if ( $enable ) {
 			$this->skin->feedback('maintenance_start');
 			// Create maintenance file to signal that we are upgrading
diff --git wp-admin/includes/update-core.php wp-admin/includes/update-core.php
index 9f17a08..cc01e27 100644
--- wp-admin/includes/update-core.php
+++ wp-admin/includes/update-core.php
@@ -743,7 +743,7 @@ if ( ! defined( 'CORE_UPGRADE_SKIP_NEW_BUNDLED' ) || CORE_UPGRADE_SKIP_NEW_BUNDL
 /**
  * Upgrade the core of WordPress.
  *
- * This will create a .maintenance file at the base of the WordPress directory
+ * This will create a wordpress.maintenance file at the base of the WordPress directory
  * to ensure that people can not access the web site, when the files are being
  * copied to their locations.
  *
@@ -756,14 +756,14 @@ if ( ! defined( 'CORE_UPGRADE_SKIP_NEW_BUNDLED' ) || CORE_UPGRADE_SKIP_NEW_BUNDL
  * The steps for the upgrader for after the new release is downloaded and
  * unzipped is:
  *   1. Test unzipped location for select files to ensure that unzipped worked.
- *   2. Create the .maintenance file in current WordPress base.
+ *   2. Create the wordpress.maintenance file in current WordPress base.
  *   3. Copy new WordPress directory over old WordPress files.
  *   4. Upgrade WordPress to new version.
  *     4.1. Copy all files/folders other than wp-content
  *     4.2. Copy any language files to WP_LANG_DIR (which may differ from WP_CONTENT_DIR
  *     4.3. Copy any new bundled themes/plugins to their respective locations
  *   5. Delete new WordPress directory path.
- *   6. Delete .maintenance file.
+ *   6. Delete wordpress.maintenance file.
  *   7. Remove old files.
  *   8. Delete 'update_core' option.
  *
@@ -929,7 +929,7 @@ function update_core($from, $to) {
 	apply_filters( 'update_feedback', __( 'Enabling Maintenance mode…' ) );
 	// Create maintenance file to signal that we are upgrading
 	$maintenance_string = '<?php $upgrading = ' . time() . '; ?>';
-	$maintenance_file = $to . '.maintenance';
+	$maintenance_file = $to . 'wordpress.maintenance';
 	$wp_filesystem->delete($maintenance_file);
 	$wp_filesystem->put_contents($maintenance_file, $maintenance_string, FS_CHMOD_FILE);
 
diff --git wp-includes/load.php wp-includes/load.php
index 9d247ba..2f3e987 100644
--- wp-includes/load.php
+++ wp-includes/load.php
@@ -160,7 +160,9 @@ function wp_favicon_request() {
 /**
  * Die with a maintenance message when conditions are met.
  *
- * Checks for a file in the WordPress root directory named ".maintenance".
+ * Checks for a file in the WordPress root directory named "wordpress.maintenance"
+ * or '.maintenance' (deprecated).
+ *
  * This file will contain the variable $upgrading, set to the time the file
  * was created. If the file was created less than 10 minutes ago, WordPress
  * enters maintenance mode and displays a message.
@@ -174,12 +176,16 @@ function wp_favicon_request() {
  * @global int $upgrading the unix timestamp marking when upgrading WordPress began.
  */
 function wp_maintenance() {
-	if ( ! file_exists( ABSPATH . '.maintenance' ) || wp_installing() )
+	if ( ( ! file_exists( ABSPATH . 'wordpress.maintenance' ) && ! file_exists( ABSPATH . '.maintenance' ) ) || wp_installing() )
 		return;
 
 	global $upgrading;
+	if ( file_exists( ABSPATH . 'wordpress.maintenance' ) ) {
+		include ( ABSPATH . 'wordpress.maintenance' );
+	} else {
+		include ( ABSPATH . '.maintenance' );
+	}
 
-	include( ABSPATH . '.maintenance' );
 	// If the $upgrading timestamp is older than 10 minutes, don't die.
 	if ( ( time() - $upgrading ) >= 600 )
 		return;