diff --git a/lib/model-definition.js b/lib/model-definition.js
index ae53a1be..32bbcd1c 100644
--- a/lib/model-definition.js
+++ b/lib/model-definition.js
@@ -210,6 +210,7 @@ ModelDefinition.prototype.build = function (forceRebuild) {
     this.properties = null;
     this.relations = [];
     this._ids = null;
+    this.json = null;
   }
   if (this.properties) {
     return this.properties;
diff --git a/test/model-definition.test.js b/test/model-definition.test.js
index 080685e4..e7f22ff1 100644
--- a/test/model-definition.test.js
+++ b/test/model-definition.test.js
@@ -55,6 +55,8 @@ describe('ModelDefinition class', function () {
     });
 
     User.build();
+    
+    var json = User.toJSON();
 
     User.defineProperty("id", {type: "number", id: true});
     assert.equal(User.properties.name.type, String);
@@ -62,8 +64,12 @@ describe('ModelDefinition class', function () {
     assert.equal(User.properties.approved.type, Boolean);
     assert.equal(User.properties.joinedAt.type, Date);
     assert.equal(User.properties.age.type, Number);
-
+    
     assert.equal(User.properties.id.type, Number);
+    
+    json = User.toJSON();
+    assert.deepEqual(json.properties.id, {type: 'Number', id: true});
+    
     done();
 
   });