diff --git a/includes/rest/class-inbox.php b/includes/rest/class-inbox.php
index 7cdb0b7..b530a37 100644
--- a/includes/rest/class-inbox.php
+++ b/includes/rest/class-inbox.php
@@ -126,7 +126,7 @@ class Inbox {
 	public static function user_inbox_post( $request ) {
 
 		$user_id = $request->get_param( 'user_id' );
-		$user    = Users::get_by_various( $user_id );
+		$user    = User_Collection::get_by_various( $user_id );
 
 		if ( is_wp_error( $user ) ) {
 			return $user;