Index: wp-includes/post.php
===================================================================
--- wp-includes/post.php	(revision 12103)
+++ wp-includes/post.php	(working copy)
@@ -1665,8 +1665,10 @@
 		clean_post_cache($post_ID);
 
 	// Set GUID
-	if ( !$update && '' == $current_guid )
-		$wpdb->update( $wpdb->posts, array( 'guid' => get_permalink( $post_ID ) ), $where );
+	if ( !$update && '' == $current_guid ) {
+		$uuid = $wpdb->get_var('SELECT UUID()');
+		$wpdb->update( $wpdb->posts, array( 'guid' => $uuid ), $where );
+	}
 
 	$post = get_post($post_ID);
 
Index: wp-admin/includes/upgrade.php
===================================================================
--- wp-admin/includes/upgrade.php	(revision 12103)
+++ wp-admin/includes/upgrade.php	(working copy)
@@ -156,7 +156,7 @@
 	// First post
 	$now = date('Y-m-d H:i:s');
 	$now_gmt = gmdate('Y-m-d H:i:s');
-	$first_post_guid = get_option('home') . '/?p=1';
+	$first_post_guid = $wpdb->get_var('SELECT UUID()');
 
 	$wpdb->insert( $wpdb->posts, array(
 								'post_author' => $user_id,
@@ -188,7 +188,7 @@
 								'comment_content' => __('Hi, this is a comment.<br />To delete a comment, just log in and view the post&#039;s comments. There you will have the option to edit or delete them.')
 								));
 	// First Page
-	$first_post_guid = get_option('home') . '/?page_id=2';
+	$first_post_guid = $wpdb->get_var('SELECT UUID()');
 	$wpdb->insert( $wpdb->posts, array(
 								'post_author' => $user_id,
 								'post_date' => $now,