diff --git a/packages/next/lib/load-custom-routes.ts b/packages/next/lib/load-custom-routes.ts
index 36a226b81221..caa0e2f8307c 100644
--- a/packages/next/lib/load-custom-routes.ts
+++ b/packages/next/lib/load-custom-routes.ts
@@ -42,9 +42,16 @@ export type Redirect = {
   basePath?: false
   locale?: false
   has?: RouteHas[]
-  statusCode?: number
-  permanent?: boolean
-}
+} & (
+  | {
+      statusCode?: never
+      permanent: boolean
+    }
+  | {
+      statusCode: number
+      permanent?: never
+    }
+)
 
 export const allowedStatusCodes = new Set([301, 302, 303, 307, 308])
 const allowedHasTypes = new Set(['header', 'cookie', 'query', 'host'])