diff --git a/src/observe.js b/src/observe.js
index 999cbec..bbc415d 100644
--- a/src/observe.js
+++ b/src/observe.js
@@ -310,7 +310,6 @@
     var added = {};
     var removed = {};
     var changed = {};
-    var oldObjectHas = {};
 
     for (var prop in oldObject) {
       var newValue = object[prop];