diff --git a/packages/core/parcel-bundler/src/Server.js b/packages/core/parcel-bundler/src/Server.js
index 4e9aacda78d..8e87fbc9a40 100644
--- a/packages/core/parcel-bundler/src/Server.js
+++ b/packages/core/parcel-bundler/src/Server.js
@@ -79,6 +79,7 @@ function middleware(bundler) {
     }
 
     function send500(error) {
+      setHeaders(res);
       res.setHeader('Content-Type', 'text/html; charset=utf-8');
       res.writeHead(500);
       let errorMesssge = '<h1>🚨 Build Error</h1>';
@@ -106,7 +107,7 @@ function middleware(bundler) {
       if (next) {
         return next();
       }
-
+      setHeaders(res);
       res.writeHead(404);
       res.end();
     }