diff --git a/wp-includes/ms-functions.php b/wp-includes/ms-functions.php
index eb44be0290..830bb5cc28 100644
--- a/wp-includes/ms-functions.php
+++ b/wp-includes/ms-functions.php
@@ -1476,7 +1476,8 @@ function update_posts_count( $deprecated = '' ) {
 function wpmu_log_new_registrations( $blog_id, $user_id ) {
 	global $wpdb;
 	$user = get_userdata( (int) $user_id );
-	$wpdb->insert( $wpdb->registration_log, array('email' => $user->user_email, 'IP' => preg_replace( '/[^0-9., ]/', '', wp_unslash( $_SERVER['REMOTE_ADDR'] ) ), 'blog_id' => $blog_id, 'date_registered' => current_time('mysql')) );
+	if ( $user )
+		$wpdb->insert( $wpdb->registration_log, array('email' => $user->user_email, 'IP' => preg_replace( '/[^0-9., ]/', '', wp_unslash( $_SERVER['REMOTE_ADDR'] ) ), 'blog_id' => $blog_id, 'date_registered' => current_time('mysql')) );
 }
 
 /**