diff --git a/lib/filters.js b/lib/filters.js
index 73dc64e1..ab856ba2 100644
--- a/lib/filters.js
+++ b/lib/filters.js
@@ -250,14 +250,14 @@ exports.groupBy = function (input, key) {
     }
 
     var keyname = value[key],
-      newVal = utils.extend({}, value);
-    delete value[key];
+      newValue = utils.extend({}, value);
+    delete newValue[key];
 
     if (!out[keyname]) {
       out[keyname] = [];
     }
 
-    out[keyname].push(value);
+    out[keyname].push(newValue);
   });
 
   return out;