diff --git a/index.mjs b/index.mjs
index 3c649f1..022f79f 100644
--- a/index.mjs
+++ b/index.mjs
@@ -2168,6 +2168,9 @@ class User {
   }
 
   static async isUser (object) {
+    if (!object) {
+      return false
+    }
     const id = await object.id()
     const row = await db.get('SELECT actorId FROM user WHERE actorId = ?', [id])
     return !!row