diff --git a/source/Ox.js b/source/Ox.js
index 09b1f291..6c5348b5 100644
--- a/source/Ox.js
+++ b/source/Ox.js
@@ -746,6 +746,7 @@ Ox.map = function(obj, fn) {
     var isObject = Ox.isObject(obj),
         ret = isObject ? {} : [];
     Ox.forEach(obj, function(val, key) {
+        var v;
         if ((v = fn(val, key)) !== null) {
             ret[isObject ? key : ret.length] = v;
         }