diff --git a/lib/zoneinfo.js b/lib/zoneinfo.js
index <HASH>..<HASH> 100644
--- a/lib/zoneinfo.js
+++ b/lib/zoneinfo.js
@@ -171,7 +171,7 @@ var TZDate = module.exports = function (args){
                 return;
             }
             
-            if (Object.keys(self._formats).indexOf(chr) > -1)
+            if (self._formats[chr])
             {
                 var realslashes = Math.floor(slashct / 2);
                 for (var i = 0; i < realslashes; i++){ fmt_string += "\\"; }
No need to do indexOf when just trying to access works fine