diff --git a/packages/next/src/server/app-render/action-handler.ts b/packages/next/src/server/app-render/action-handler.ts
index 35225d2334e252..58d4286f5feeca 100644
--- a/packages/next/src/server/app-render/action-handler.ts
+++ b/packages/next/src/server/app-render/action-handler.ts
@@ -488,9 +488,7 @@ export async function handleAction({
       ? new URL(req.headers['origin']).host
       : undefined
 
-  const forwardedHostHeader = req.headers['x-forwarded-host'] as
-    | string
-    | undefined
+  const forwardedHostHeader = req.headers['x-forwarded-host']?.[0]
   const hostHeader = req.headers['host']
   const host: Host = forwardedHostHeader
     ? {