diff --git a/lib/server.js b/lib/server.js
index cc779802..b4410434 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -57,26 +57,17 @@ Server.prototype.__proto__ = EventEmitter.prototype;
 Server.prototype.clients;
 
 /**
- * Returns a list of available transports for upgrade.
+ * Returns a list of available transports for upgrade given a certain transport.
  *
  * @return {Array}
  * @api public
  */
 
-Server.prototype.upgrades = function () {
-  var available = this.transports
-    , upgrades = []
-
-  for (var i in transports) {
-    if (~available.indexOf(i) && transports[i].prototype.isUpgrade) {
-      upgrades.push(i);
-    }
-  }
-
-  return upgrades;
+Server.prototype.upgrades = function (transport) {
+  if (!this.allowUpgrades) return [];
+  return transports[transport].upgradesTo || [];
 };
 
-
 /**
  * Verifies a request.
  *