diff --git a/middleware/trace.js b/middleware/trace.js
index 24cbf38f4..6ac6f4b2c 100644
--- a/middleware/trace.js
+++ b/middleware/trace.js
@@ -3,5 +3,9 @@ const uuid = require('uuid/v1');
 // Trace middleware attaches a request id to each incoming request.
 module.exports = (req, res, next) => {
   req.id = uuid();
+
+  // Add the context ID to the request as an HTTP header.
+  res.set('X-Talk-Trace-ID', req.id);
+
   next();
 };