diff --git a/packages/webapp/webapp_server.js b/packages/webapp/webapp_server.js
index d5b1d5c586..0b3d9eda99 100644
--- a/packages/webapp/webapp_server.js
+++ b/packages/webapp/webapp_server.js
@@ -659,8 +659,13 @@ var runWebAppServer = function () {
     if (request.url.query && request.url.query['meteor_css_resource']) {
       // In this case, we're requesting a CSS resource in the meteor-specific
       // way, but we don't have it.  Serve a static css file that indicates that
-      // we didn't have it, so we can detect that and refresh.
+      // we didn't have it, so we can detect that and refresh.  Make sure
+      // that any proxies or CDNs don't cache this error!  (Normally proxies
+      // or CDNs are smart enough not to cache error pages, but in order to
+      // make this hack work, we need to return the CSS file as a 200, which
+      // would otherwise be cached.)
       headers['Content-Type'] = 'text/css; charset=utf-8';
+      headers['Cache-Control'] = 'no-cache';
       res.writeHead(200, headers);
       res.write(".meteor-css-not-found-error { width: 0px;}");
       res.end();