diff --git a/src/Module/ActivityPub/Objects.php b/src/Module/ActivityPub/Objects.php
index 34d4609511..f93c8b9574 100644
--- a/src/Module/ActivityPub/Objects.php
+++ b/src/Module/ActivityPub/Objects.php
@@ -46,6 +46,8 @@ class Objects extends BaseModule
 			throw new HTTPException\BadRequestException();
 		}
 
+		header('Vary: Accept', false);
+
 		if (!ActivityPub::isRequest()) {
 			DI::baseUrl()->redirect(str_replace('objects/', 'display/', DI::args()->getQueryString()));
 		}
diff --git a/src/Module/Friendica.php b/src/Module/Friendica.php
index 90869878e4..73d5f633cd 100644
--- a/src/Module/Friendica.php
+++ b/src/Module/Friendica.php
@@ -115,6 +115,8 @@ class Friendica extends BaseModule
 
 	protected function rawContent(array $request = [])
 	{
+		header('Vary: Accept', false);
+
 		// @TODO: Replace with parameter from router
 		if (DI::args()->getArgc() <= 1 || (DI::args()->getArgv()[1] !== 'json')) {
 			if (!ActivityPub::isRequest()) {
diff --git a/src/Module/Item/Display.php b/src/Module/Item/Display.php
index b2ed43c5b5..a0d1ecbf56 100644
--- a/src/Module/Item/Display.php
+++ b/src/Module/Item/Display.php
@@ -88,6 +88,8 @@ class Display extends BaseModule
 
 	protected function content(array $request = []): string
 	{
+		header('Vary: Accept', false);
+
 		if (ActivityPub::isRequest()) {
 			$this->baseUrl->redirect(str_replace('display/', 'objects/', $this->args->getQueryString()));
 		}
diff --git a/src/Module/Profile/Profile.php b/src/Module/Profile/Profile.php
index 5e5028cb86..31ef8d05bf 100644
--- a/src/Module/Profile/Profile.php
+++ b/src/Module/Profile/Profile.php
@@ -80,6 +80,8 @@ class Profile extends BaseProfile
 
 	protected function rawContent(array $request = [])
 	{
+		header('Vary: Accept', false);
+
 		if (ActivityPub::isRequest()) {
 			$user = $this->database->selectFirst('user', ['uid'], ['nickname' => $this->parameters['nickname'] ?? '', 'account_removed' => false]);
 			if ($user) {
diff --git a/src/Module/Xrd.php b/src/Module/Xrd.php
index 6a4c0e860d..3267e9e9a2 100644
--- a/src/Module/Xrd.php
+++ b/src/Module/Xrd.php
@@ -80,6 +80,8 @@ class Xrd extends BaseModule
 			throw new NotFoundException('Invalid host name for xrd query: ' . $host);
 		}
 
+		header('Vary: Accept', false);
+
 		if ($name == User::getActorName()) {
 			$owner = User::getSystemAccount();
 			if (empty($owner)) {
@@ -326,7 +328,6 @@ class Xrd extends BaseModule
 		]);
 
 		header('Access-Control-Allow-Origin: *');
-
 		System::httpExit($xmlString, Response::TYPE_XML, 'application/xrd+xml');
 	}
 }