diff --git a/lib/index.js b/lib/index.js
index bc258988..0ac79e2f 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -50,7 +50,7 @@ module.exports = {
    * ```
    */
   loop: function(opts, callback) {
-    if (opts && callback === undefined && (!opts.frame && !opts.hand)) {
+    if (opts && callback === undefined &&  ( ({}).toString.call(opts) === '[object Function]' ) ) {
       callback = opts;
       opts = {};
     }