diff --git a/includes/class-activity.php b/includes/class-activity.php
index 354159d..2a18403 100644
--- a/includes/class-activity.php
+++ b/includes/class-activity.php
@@ -73,13 +73,19 @@ class Activity {
 	}
 
 	public function to_simple_array() {
-		return array(
+		$activity = array(
 			'@context' => $this->context,
 			'type' => $this->type,
 			'actor' => $this->actor,
 			'object' => $this->object,
 			'to' => $this->to,
 		);
+
+		if ( $this->id ) {
+			$activity['id'] = $this->id;
+		}
+
+		return $activity;
 	}
 
 	public function to_simple_json() {
diff --git a/includes/rest/class-inbox.php b/includes/rest/class-inbox.php
index e65171b..1391c64 100644
--- a/includes/rest/class-inbox.php
+++ b/includes/rest/class-inbox.php
@@ -160,6 +160,7 @@ class Inbox {
 		$activity->set_object( $object );
 		$activity->set_actor( get_author_posts_url( $user_id ) );
 		$activity->set_to( $object['actor'] );
+		$activity->set_id( get_author_posts_url( $user_id ) . '#follow' . preg_replace( '~^https?://~', '', $object['actor'] ) );
 
 		$activity = $activity->to_simple_json();