diff --git a/src/activitypub/helpers.js b/src/activitypub/helpers.js
index 5a50e2e8ed..79aebc25dc 100644
--- a/src/activitypub/helpers.js
+++ b/src/activitypub/helpers.js
@@ -64,6 +64,11 @@ Helpers.isUri = (value) => {
 	});
 };
 
+Helpers.assertAccept = accept => (accept && accept.split(',').some((value) => {
+	const parts = value.split(';').map(v => v.trim());
+	return activitypub._constants.acceptableTypes.includes(value || parts[0]);
+}));
+
 Helpers.isWebfinger = (value) => {
 	// N.B. returns normalized handle, so truthy check!
 	if (webfingerRegex.test(value) && !Helpers.isUri(value)) {
diff --git a/src/controllers/404.js b/src/controllers/404.js
index becc206e76..bed1a085e3 100644
--- a/src/controllers/404.js
+++ b/src/controllers/404.js
@@ -6,6 +6,7 @@ const validator = require('validator');
 
 const meta = require('../meta');
 const plugins = require('../plugins');
+const activitypub = require('../activitypub');
 const middleware = require('../middleware');
 const helpers = require('../middleware/helpers');
 const { secureRandom } = require('../utils');
@@ -24,6 +25,12 @@ exports.handle404 = helpers.try(async (req, res) => {
 
 	if (isClientScript.test(req.url)) {
 		res.type('text/javascript').status(404).send('Not Found');
+	} else if (
+		activitypub.helpers.assertAccept(req.headers.accept) ||
+		(req.headers['Content-Type'] && activitypub._constants.acceptableTypes.includes(req.headers['Content-Type']))
+	) {
+		// todo: separate logging of AP 404s
+		res.sendStatus(404);
 	} else if (
 		!res.locals.isAPI && (
 			req.path.startsWith(`${relativePath}/assets/uploads`) ||
diff --git a/src/middleware/activitypub.js b/src/middleware/activitypub.js
index f9b8dcd009..ee7d8a2460 100644
--- a/src/middleware/activitypub.js
+++ b/src/middleware/activitypub.js
@@ -16,10 +16,8 @@ middleware.assertS2S = async function (req, res, next) {
 		return next('route');
 	}
 
-	const pass = (accept && accept.split(',').some((value) => {
-		const parts = value.split(';').map(v => v.trim());
-		return activitypub._constants.acceptableTypes.includes(value || parts[0]);
-	})) || (contentType && activitypub._constants.acceptableTypes.includes(contentType));
+	const pass = activitypub.helpers.assertAccepts(accept) ||
+		(contentType && activitypub._constants.acceptableTypes.includes(contentType));
 
 	if (!pass) {
 		return next('route');