diff --git a/.travis.yml b/.travis.yml
index 1dc3da5..a2bf59d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,6 +6,7 @@ notifications:
 
 node_js:
   - 'iojs-2'
+  - '4.2.1'
 
 install:
   - npm install
diff --git a/History.md b/History.md
index 6e1267a..2f824c7 100644
--- a/History.md
+++ b/History.md
@@ -1,3 +1,7 @@
+## 0.7.2
+
+- fix: merge [52](https://github.com/shepherdwind/velocity.js/pull/52)
+
 ## 0.7.1
 
 - fix: merge [51](https://github.com/shepherdwind/velocity.js/pull/51)
diff --git a/package.json b/package.json
index e47adf4..ae528b8 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "velocityjs",
   "description": "Velocity Template Language(VTL) for JavaScript",
-  "version": "0.7.1",
+  "version": "0.7.2",
   "keywords": [
     "velocity template"
   ],
diff --git a/src/compile/references.js b/src/compile/references.js
index 643cca2..bb625ef 100644
--- a/src/compile/references.js
+++ b/src/compile/references.js
@@ -270,7 +270,7 @@ module.exports = function(Velocity, utils) {
 
           var that = this;
 
-          if(typeof baseRef === 'object'){
+          if(typeof baseRef === 'object' && baseRef){
             baseRef.eval = function() {
               return that.eval.apply(that, arguments);
             };