diff --git a/app/Services/Link/LinkPlatformProxy.php b/app/Services/Link/LinkPlatformProxy.php
index 3c911ff..b2a3b0e 100644
--- a/app/Services/Link/LinkPlatformProxy.php
+++ b/app/Services/Link/LinkPlatformProxy.php
@@ -57,15 +57,13 @@ class LinkPlatformProxy
     /** @return array<string, string> */
     private function forwardHeaders(Request $request): array
     {
-        $headers = [];
-        foreach (['Accept', 'Accept-Language', 'User-Agent', 'Referer'] as $name) {
-            $value = $request->header($name);
-            if ($value !== null) {
-                $headers[$name] = $value;
-            }
-        }
-
-        return $headers;
+        return array_filter([
+            'Accept' => $request->header('Accept'),
+            'Accept-Language' => $request->header('Accept-Language'),
+            'User-Agent' => $request->header('User-Agent'),
+            'Referer' => $request->header('Referer'),
+            'X-Ladill-Internal' => '1',
+        ]);
     }
 
     /** @param array<string, array<int, string>> $headers */
diff --git a/tests/Feature/LinkRedirectTest.php b/tests/Feature/LinkRedirectTest.php
index 8374b09..862fa69 100644
--- a/tests/Feature/LinkRedirectTest.php
+++ b/tests/Feature/LinkRedirectTest.php
@@ -59,5 +59,10 @@ class LinkRedirectTest extends TestCase
         $this->get('https://ladl.link/qrpage')
             ->assertOk()
             ->assertSee('QR page');
+
+        Http::assertSent(function ($request) {
+            return $request->url() === 'https://ladill.com/q/qrpage'
+                && $request->hasHeader('X-Ladill-Internal', '1');
+        });
     }
 }