From 3ba0a47a288165abc5ab1643f9b98aa1efc4d7b8 Mon Sep 17 00:00:00 2001
From: Zakir Jiwani <108548454+JiwaniZakir@users.noreply.github.com>
Date: Tue, 17 Mar 2026 04:13:33 +0000
Subject: [PATCH] fix: fallback to original value when mime.contentType returns
 false in res.set

---
 lib/response.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/response.js b/lib/response.js
index f965e539dd2..bc2bc6fb438 100644
--- a/lib/response.js
+++ b/lib/response.js
@@ -673,7 +673,7 @@ res.header = function header(field, val) {
       if (Array.isArray(value)) {
         throw new TypeError('Content-Type cannot be set to an Array');
       }
-      value = mime.contentType(value)
+      value = mime.contentType(value) || value
     }
 
     this.setHeader(field, value);