diff --git a/wp-includes/update.php b/wp-includes/update.php
index a8e983a070..756565b1d3 100644
--- a/wp-includes/update.php
+++ b/wp-includes/update.php
@@ -213,10 +213,10 @@ function wp_update_themes( ) {
 	$themes = array( );
 	$themes['current_theme'] = (array) $current_theme;
 	foreach( (array) $installed_themes as $theme_title => $theme ) {
-		$themes[$theme['Template']] = array( );
+		$themes[$theme['Stylesheet']] = array( );
 
 		foreach( (array) $theme as $key => $value ) {
-			$themes[$theme['Template']][$key] = $value;
+			$themes[$theme['Stylesheet']][$key] = $value;
 		}
 	}
 
@@ -310,4 +310,4 @@ if ( !wp_next_scheduled('wp_update_plugins') && !defined('WP_INSTALLING') )
 if ( !wp_next_scheduled('wp_update_themes') && !defined('WP_INSTALLING') )
 	wp_schedule_event(time(), 'twicedaily', 'wp_update_themes');
 
-?>
\ No newline at end of file
+?>