diff --git a/packages/mitmproxy/src/lib/proxy/mitmproxy/createRequestHandler.js b/packages/mitmproxy/src/lib/proxy/mitmproxy/createRequestHandler.js
index 0f31424..08974d6 100644
--- a/packages/mitmproxy/src/lib/proxy/mitmproxy/createRequestHandler.js
+++ b/packages/mitmproxy/src/lib/proxy/mitmproxy/createRequestHandler.js
@@ -128,6 +128,7 @@ module.exports = function createRequestHandler (createIntercepts, middlewares, e
           // log.debug('rOptions:', rOptions.hostname + rOptions.path, '\r\n', rOptions)
           // log.debug('agent:', rOptions.agent)
           // log.debug('agent.options:', rOptions.agent.options)
+          res.setHeader('DS-Proxy-Request', rOptions.hostname)
           proxyReq = (rOptions.protocol === 'https:' ? https : http).request(rOptions, (proxyRes) => {
             const cost = new Date() - start
             if (rOptions.protocol === 'https:') {