Index: wp-admin/includes/schema.php
===================================================================
--- wp-admin/includes/schema.php	(revision 15237)
+++ wp-admin/includes/schema.php	(working copy)
@@ -663,7 +663,7 @@
 		$wpdb->insert( $wpdb->site, array( 'domain' => $domain, 'path' => $path ) );
 		$network_id = $wpdb->insert_id;
 	} else {
-		$wpdb->insert( $wpdb->site, array( 'domain' => $domain, 'path' => $path, 'network_id' => $network_id ) );
+		$wpdb->insert( $wpdb->site, array( 'domain' => $domain, 'path' => $path, 'id' => $network_id ) );
 	}
 
 	if ( !is_multisite() ) {