diff --git a/modules/di/src/key.js b/modules/di/src/key.js
index 442a41a118..01fc422f5f 100644
--- a/modules/di/src/key.js
+++ b/modules/di/src/key.js
@@ -1,10 +1,13 @@
 import {MapWrapper} from 'facade/collection';
-import {int, bool} from 'facade/lang';
+import {FIELD, int, bool} from 'facade/lang';
 
 var _allKeys = {};
 var _id:int = 0;
 
 //TODO: vsavkin: move to binding once cyclic deps are supported
+@FIELD('final key:Key')
+@FIELD('final asFuture:bool')
+@FIELD('final lazy:bool')
 export class Dependency {
   constructor(key:Key, asFuture:bool, lazy:bool){
     this.key = key;
@@ -13,6 +16,8 @@ export class Dependency {
   }
 }
 
+@FIELD('final token')
+@FIELD('final id:int')
 export class Key {
   constructor(token, id:int) {
     this.token = token;