diff --git a/wp-includes/class-wp-xmlrpc-server.php b/wp-includes/class-wp-xmlrpc-server.php
index a4ba0f883d..24807cd2ab 100644
--- a/wp-includes/class-wp-xmlrpc-server.php
+++ b/wp-includes/class-wp-xmlrpc-server.php
@@ -527,7 +527,7 @@ class wp_xmlrpc_server extends IXR_Server {
 				'wp_page_parent_id'		=> $page->post_parent,
 				'wp_page_parent_title'	=> $parent_title,
 				'wp_page_order'			=> $page->menu_order,
-				'wp_author_id'			=> $author->ID,
+				'wp_author_id'			=> (string) $author->ID,
 				'wp_author_display_name'	=> $author->display_name,
 				'date_created_gmt'		=> new IXR_Date($page_date_gmt),
 				'custom_fields'			=> $this->get_custom_fields($page_id),
@@ -2850,7 +2850,7 @@ class wp_xmlrpc_server extends IXR_Server {
 				'mt_keywords' => $tagnames,
 				'wp_slug' => $postdata['post_name'],
 				'wp_password' => $postdata['post_password'],
-				'wp_author_id' => $author->ID,
+				'wp_author_id' => (string) $author->ID,
 				'wp_author_display_name'	=> $author->display_name,
 				'date_created_gmt' => new IXR_Date($post_date_gmt),
 				'post_status' => $postdata['post_status'],
@@ -2960,7 +2960,7 @@ class wp_xmlrpc_server extends IXR_Server {
 				'mt_keywords' => $tagnames,
 				'wp_slug' => $entry['post_name'],
 				'wp_password' => $entry['post_password'],
-				'wp_author_id' => $author->ID,
+				'wp_author_id' => (string) $author->ID,
 				'wp_author_display_name' => $author->display_name,
 				'date_created_gmt' => new IXR_Date($post_date_gmt),
 				'post_status' => $entry['post_status'],