diff --git a/packages/kit/test/apps/basics/src/routes/headers/invalid/+server.js b/packages/kit/test/apps/basics/src/routes/headers/invalid/+server.js
new file mode 100644
index 000000000000..b7cb2c584df0
--- /dev/null
+++ b/packages/kit/test/apps/basics/src/routes/headers/invalid/+server.js
@@ -0,0 +1,10 @@
+export function GET({ setHeaders }) {
+	globalThis.__SVELTEKIT_DEV__ = true;
+
+	setHeaders({
+		'cache-control': 'totally-invalid',
+		'content-type': 'not-a-real-type'
+	});
+
+	return new Response('Testing invalid headers');
+}