diff --git wp-admin/includes/theme.php wp-admin/includes/theme.php
index 315f021386982a01cd9cc089a69825534a1c7586..e10c9fed0618d1b7825fff2a6d2cce3630772a95 100644
--- wp-admin/includes/theme.php
+++ wp-admin/includes/theme.php
@@ -137,6 +137,7 @@ function theme_update_available( $theme ) {
 			else
 				printf( '<p><strong>' . __('There is a new version of %1$s available. <a href="%2$s" class="thickbox" title="%1$s">View version %3$s details</a> or <a href="%4$s" %5$s>update now</a>.') . '</strong></p>', $theme_name, $details_url, $update['new_version'], $update_url, $update_onclick );
 		}
+		do_action( "in_theme_update_message-$stylesheet", $theme, $update );
 	}
 }