Index: src/wp-includes/user.php
===================================================================
--- src/wp-includes/user.php	(revision 43555)
+++ src/wp-includes/user.php	(working copy)
@@ -3666,7 +3666,7 @@
 	 */
 	public function __construct( $post ) {
 		$this->ID                  = $post->ID;
-		$this->user_id             = $post->post_author;
+		$this->user_id             = (int) $post->post_author;
 		$this->email               = $post->post_title;
 		$this->action_name         = $post->post_name;
 		$this->status              = $post->post_status;