diff --git a/backbone.js b/backbone.js
index ebb04979..20d1e63b 100644
--- a/backbone.js
+++ b/backbone.js
@@ -374,6 +374,12 @@
           changed[attr] = now[attr];
         }
       }
+      for (attr in old){
+        if (!(attr in now)){
+          changed = changed || {};
+          changed[attr] = void 0;
+        }
+      }
       return changed;
     },
 
diff --git a/test/model.js b/test/model.js
index 7ad0d71f..bfb499ea 100644
--- a/test/model.js
+++ b/test/model.js
@@ -170,6 +170,14 @@ $(document).ready(function() {
     equals(i, 2, 'Unset does not fire an event for missing attributes.');
   });
 
+  test("Model: unset and changedAttributes", function() {
+    var model = new Backbone.Model({a: 1});
+    model.unset('a', {silent: true});
+    var changedAttributes = model.changedAttributes();
+    ok('a' in changedAttributes, 'changedAttributes should contain unset properties');
+    equals(changedAttributes.a, undefined);
+  });
+
   test("Model: using a non-default id attribute.", function() {
     var MongoModel = Backbone.Model.extend({idAttribute : '_id'});
     var model = new MongoModel({id: 'eye-dee', _id: 25, title: 'Model'});