diff --git a/src/misc/is-objectid.ts b/src/misc/is-objectid.ts
index c3148a778..a77c4ee2d 100644
--- a/src/misc/is-objectid.ts
+++ b/src/misc/is-objectid.ts
@@ -1,5 +1,5 @@
 import { ObjectID } from 'mongodb';
 
 export default function(x: any): x is ObjectID {
-	return x.hasOwnProperty('toHexString') || x.hasOwnProperty('_bsontype');
+	return x && typeof x === 'object' && (x.hasOwnProperty('toHexString') || x.hasOwnProperty('_bsontype'));
 }