diff --git a/packages/backend/src/misc/fetch.ts b/packages/backend/src/misc/fetch.ts
index 1cbaa78c4..46379af1a 100644
--- a/packages/backend/src/misc/fetch.ts
+++ b/packages/backend/src/misc/fetch.ts
@@ -51,7 +51,10 @@ export async function getJsonActivity(
 	if (contentType == null || (contentType !== 'application/activity+json' && !contentType.startsWith('application/activity+json;') && contentType !== 'application/ld+json' && !contentType.startsWith('application/ld+json;')))
 		throw new Error(`getJsonActivity response had unexpected content-type: ${contentType}`);
 
-	return await res.json();
+	return {
+		finalUrl: res.url,
+		content: await res.json()
+	}
 }
 
 export async function getHtml(
diff --git a/packages/backend/src/remote/activitypub/request.ts b/packages/backend/src/remote/activitypub/request.ts
index d4996c5db..b5d089a92 100644
--- a/packages/backend/src/remote/activitypub/request.ts
+++ b/packages/backend/src/remote/activitypub/request.ts
@@ -69,5 +69,8 @@ export async function signedGet(url: string, user: { id: User["id"] }, redirects
 	if (contentType == null || (contentType !== 'application/activity+json' && !contentType.startsWith('application/activity+json;') && contentType !== 'application/ld+json' && !contentType.startsWith('application/ld+json;')))
 		throw new Error(`signedGet response had unexpected content-type: ${contentType}`);
 
-	return await res.json();
+	return {
+		finalUrl: res.url,
+		content: await res.json()
+	};
 }
diff --git a/packages/backend/src/remote/activitypub/resolver.ts b/packages/backend/src/remote/activitypub/resolver.ts
index 1da888dd2..a6c407be5 100644
--- a/packages/backend/src/remote/activitypub/resolver.ts
+++ b/packages/backend/src/remote/activitypub/resolver.ts
@@ -121,11 +121,12 @@ export default class Resolver {
 		apLogger.debug("Getting object from remote, authenticated as user:");
 		apLogger.debug(JSON.stringify(this.user, null, 2));
 
-		const object = (
+		const res = (
 			this.user
 				? await signedGet(value, this.user)
 				: await getJsonActivity(value)
-		) as IObject;
+		);
+		const object = res.content as IObject;
 
 		if (
 			object == null ||
@@ -138,6 +139,9 @@ export default class Resolver {
 			throw new Error("invalid response");
 		}
 
+		if (object.id != null && new URL(res.finalUrl).host != new URL(object.id).host)
+			throw new Error("Object ID host doesn't match final url host");
+
 		return object;
 	}