@@ -853,7 +853,7 @@ Client.prototype.https = function(filename){
  */
 
 Client.prototype.signedUrl = function(filename, expiration, options){
-  var epoch = Math.floor(expiration.getTime()/1000)
+  var epoch = Math.floor(+expiration/1000)
     , pathname = url.parse(filename).pathname
     , resource = '/' + this.bucket + ensureLeadingSlash(pathname);
 