diff --git a/includes/class-wc-install.php b/includes/class-wc-install.php
index 9dbf9785605..54cc0c98fc7 100644
--- a/includes/class-wc-install.php
+++ b/includes/class-wc-install.php
@@ -81,6 +81,7 @@ class WC_Install {
 		),
 		'3.1.0' => array(
 			'wc_update_310_downloadable_products',
+			'wc_update_310_old_comments',
 			'wc_update_310_db_version',
 		),
 	);
diff --git a/includes/wc-update-functions.php b/includes/wc-update-functions.php
index 3131fd2659f..9d11f07ba98 100644
--- a/includes/wc-update-functions.php
+++ b/includes/wc-update-functions.php
@@ -1112,6 +1112,15 @@ function wc_update_310_downloadable_products() {
 	}
 }
 
+/**
+ * Find old order notes and ensure they have the correct type for exclusion.
+ */
+function wc_update_310_old_comments() {
+	global $wpdb;
+
+	$wpdb->query( "UPDATE $wpdb->comments comments LEFT JOIN $wpdb->posts as posts ON comments.comment_post_ID = posts.ID SET comment_type = 'order_note' WHERE posts.post_type = 'shop_order' AND comment_type = '';" );
+}
+
 /**
  * Update DB Version.
  */