diff --git a/packages/backend/src/core/activitypub/ApRequestService.ts b/packages/backend/src/core/activitypub/ApRequestService.ts
index 9359dccc86..1b0ae6b5aa 100644
--- a/packages/backend/src/core/activitypub/ApRequestService.ts
+++ b/packages/backend/src/core/activitypub/ApRequestService.ts
@@ -40,6 +40,8 @@ export async function createSignedPost(args: { level: string; key: PrivateKey; u
 		['(request-target)', 'date', 'host', 'digest'],
 	);
 
+	delete request.headers['host'];
+
 	return {
 		request,
 		...result,
@@ -66,6 +68,8 @@ export async function createSignedGet(args: { level: string; key: PrivateKey; ur
 		['(request-target)', 'date', 'host', 'accept'],
 	);
 
+	delete request.headers['host'];
+
 	return {
 		request,
 		...result,