diff --git a/src/activitypub/instances.js b/src/activitypub/instances.js
index 548343d1bb..16765ea553 100644
--- a/src/activitypub/instances.js
+++ b/src/activitypub/instances.js
@@ -13,7 +13,7 @@ Instances.getCount = async () => db.sortedSetCard('instances:lastSeen');
 
 Instances.isAllowed = async (domain) => {
 	let { activitypubFilter: type, activitypubFilterList: list } = meta.config;
-	list = new Set(list.split('\n'));
+	list = new Set(String(list).split('\n'));
 	// eslint-disable-next-line no-bitwise
 	return list.has(domain) ^ !type;
 };