diff --git a/Makefile b/Makefile
index 0f14dac..89cc2d2 100644
--- a/Makefile
+++ b/Makefile
@@ -1,3 +1,4 @@
+TESTS = test/index.js
 
 build: components index.js
 	@component build --dev
@@ -8,4 +9,9 @@ components: component.json
 clean:
 	rm -fr build components template.js
 
-.PHONY: clean
+test:
+	@./node_modules/.bin/mocha \
+		--growl \
+		$(TESTS)
+
+.PHONY: test clean
diff --git a/index.js b/index.js
index 27fe990..c56660c 100644
--- a/index.js
+++ b/index.js
@@ -390,7 +390,6 @@ o.data = function () {
 		this._data[k] = obj[k];
 	}
     
-    Object.freeze(obj);
     this.emit("data change",this,obj);
     var root = this.root;
     if(root !== this){
diff --git a/package.json b/package.json
index 298b62d..921ead9 100644
--- a/package.json
+++ b/package.json
@@ -4,7 +4,7 @@
   "description": "tree node",
   "main": "index.js",
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "test": "make test"
   },
   "repository": {
     "type": "git",
@@ -28,5 +28,7 @@
   "dependencies": {
     "emitter-component": "~1.1.1"
   },
-  "devDependencies": {}
+  "devDependencies": {
+    "mocha": "*"
+  }
 }
diff --git a/test/index.js b/test/index.js
index 8483b7c..cb72b31 100644
--- a/test/index.js
+++ b/test/index.js
@@ -199,8 +199,18 @@ describe("Node",function(){
        
        node.data({age:12});
        assert(node.data("name") === "leo" && node.data("age") === 12);
-       
+       node.data({age:13});
+       assert(node.data("name") === "leo" && node.data("age") === 13);
        assert(node.data() === node._data);
+
+       var node2 = new Node();
+       node2.data({age:12});
+       var data = node2.data();
+       data.age = data.age + 1;
+       node2.data(data);
+       data.age = data.age + 1;
+       node2.data(data);
+       assert(data.age === 14);
     });
     
     it("#json",function(){