diff --git a/wp-includes/update.php b/wp-includes/update.php
index 61d7ca3dc..028a4d138 100644
--- a/wp-includes/update.php
+++ b/wp-includes/update.php
@@ -395,7 +395,7 @@ function wp_schedule_update_checks() {
 		wp_schedule_event(time(), 'twicedaily', 'wp_update_themes');
 }
 
-if ( ! is_main_site() )
+if ( ! is_main_site() && ! is_network_admin() )
 	return;
 
 add_action( 'admin_init', '_maybe_update_core' );