diff --git a/packages/webapp/webapp_server.js b/packages/webapp/webapp_server.js
index 961e23fafb..c897dfa62b 100644
--- a/packages/webapp/webapp_server.js
+++ b/packages/webapp/webapp_server.js
@@ -649,81 +649,83 @@ var runWebAppServer = function () {
   });
 
   app.use(function (req, res, next) {
-    if (! appUrl(req.url))
-      return next();
+    Fiber(function () {
+      if (!appUrl(req.url))
+        return next();
 
-    var headers = {
-      'Content-Type':  'text/html; charset=utf-8'
-    };
-    if (shuttingDown)
-      headers['Connection'] = 'Close';
+      var headers = {
+        'Content-Type': 'text/html; charset=utf-8'
+      };
+      if (shuttingDown)
+        headers['Connection'] = 'Close';
 
-    var request = WebApp.categorizeRequest(req);
+      var request = WebApp.categorizeRequest(req);
 
-    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.  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;}");
+      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.  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();
+        return undefined;
+      }
+
+      if (request.url.query && request.url.query['meteor_js_resource']) {
+        // Similarly, we're requesting a JS resource that we don't have.
+        // Serve an uncached 404. (We can't use the same hack we use for CSS,
+        // because actually acting on that hack requires us to have the JS
+        // already!)
+        headers['Cache-Control'] = 'no-cache';
+        res.writeHead(404, headers);
+        res.end("404 Not Found");
+        return undefined;
+      }
+
+      if (request.url.query && request.url.query['meteor_dont_serve_index']) {
+        // When downloading files during a Cordova hot code push, we need
+        // to detect if a file is not available instead of inadvertently
+        // downloading the default index page.
+        // So similar to the situation above, we serve an uncached 404.
+        headers['Cache-Control'] = 'no-cache';
+        res.writeHead(404, headers);
+        res.end("404 Not Found");
+        return undefined;
+      }
+
+      // /packages/asdfsad ... /__cordova/dafsdf.js
+      var pathname = parseurl(req).pathname;
+      var archKey = pathname.split('/')[1];
+      var archKeyCleaned = 'web.' + archKey.replace(/^__/, '');
+
+      if (!/^__/.test(archKey) || !_.has(archPath, archKeyCleaned)) {
+        archKey = WebApp.defaultArch;
+      } else {
+        archKey = archKeyCleaned;
+      }
+
+      var boilerplate;
+      try {
+        boilerplate = getBoilerplate(request, archKey);
+      } catch (e) {
+        Log.error("Error running template: " + e);
+        res.writeHead(500, headers);
+        res.end();
+        return undefined;
+      }
+
+      var statusCode = res.statusCode ? res.statusCode : 200;
+      res.writeHead(statusCode, headers);
+      res.write(boilerplate);
       res.end();
       return undefined;
-    }
-
-    if (request.url.query && request.url.query['meteor_js_resource']) {
-      // Similarly, we're requesting a JS resource that we don't have.
-      // Serve an uncached 404. (We can't use the same hack we use for CSS,
-      // because actually acting on that hack requires us to have the JS
-      // already!)
-      headers['Cache-Control'] = 'no-cache';
-      res.writeHead(404, headers);
-      res.end("404 Not Found");
-      return undefined;
-    }
-
-    if (request.url.query && request.url.query['meteor_dont_serve_index']) {
-      // When downloading files during a Cordova hot code push, we need
-      // to detect if a file is not available instead of inadvertently
-      // downloading the default index page.
-      // So similar to the situation above, we serve an uncached 404.
-      headers['Cache-Control'] = 'no-cache';
-      res.writeHead(404, headers);
-      res.end("404 Not Found");
-      return undefined;
-    }
-
-    // /packages/asdfsad ... /__cordova/dafsdf.js
-    var pathname = parseurl(req).pathname;
-    var archKey = pathname.split('/')[1];
-    var archKeyCleaned = 'web.' + archKey.replace(/^__/, '');
-
-    if (! /^__/.test(archKey) || ! _.has(archPath, archKeyCleaned)) {
-      archKey = WebApp.defaultArch;
-    } else {
-      archKey = archKeyCleaned;
-    }
-
-    var boilerplate;
-    try {
-      boilerplate = getBoilerplate(request, archKey);
-    } catch (e) {
-      Log.error("Error running template: " + e);
-      res.writeHead(500, headers);
-      res.end();
-      return undefined;
-    }
-
-    var statusCode = res.statusCode ? res.statusCode : 200;
-    res.writeHead(statusCode, headers);
-    res.write(boilerplate);
-    res.end();
-    return undefined;
+    }).run();
   });
 
   // Return 404 by default, if no other handlers serve this URL.