diff --git a/src/reactTemplates.js b/src/reactTemplates.js
index f0ec735..6006dca 100644
--- a/src/reactTemplates.js
+++ b/src/reactTemplates.js
@@ -263,6 +263,13 @@ function convertFile(source, target) {
 //        console.log('invalid file, only handle html files');
 //        return;// only handle html files
 //    }
+    var util = require('./util');
+
+    if (!util.isStale(source, target)) {
+        console.log('target file ' + target + ' is up to date, skipping');
+//        return;
+    }
+
     var html = fs.readFileSync(source).toString();
     if (!html.match(/\<\!doctype jsx/i)) {
         throw new Error('invalid file, missing header');
diff --git a/src/util.js b/src/util.js
new file mode 100644
index 0000000..ef05289
--- /dev/null
+++ b/src/util.js
@@ -0,0 +1,21 @@
+'use strict';
+var fs = require('fs');
+var path = require('path');
+
+/**
+ * @param {string} source
+ * @param {string} target
+ * @return {boolean}
+ */
+function isStale(source, target) {
+    if (!fs.existsSync(target)) {
+        return true;
+    }
+    var sourceTime = fs.statSync(source).mtime;
+    var targetTime = fs.statSync(target).mtime;
+    return sourceTime.getTime() > targetTime.getTime();
+}
+
+module.exports = {
+    isStale: isStale
+};
\ No newline at end of file
diff --git a/test/src/test.js b/test/src/test.js
index 09ead69..de9c9e3 100644
--- a/test/src/test.js
+++ b/test/src/test.js
@@ -56,3 +56,21 @@ test('html tests', function (t) {
 
 });
 
+test('util.isStale', function (t) {
+    t.plan(2);
+    var a = path.join(dataPath, 'a.tmp');
+    var b = path.join(dataPath, 'b.tmp');
+
+    var mtime1 = new Date(1995, 11, 17, 3, 24, 0);
+    fs.utimesSync(a, mtime1, mtime1);
+
+    var mtime2 = new Date(1995, 11, 17, 3, 24, 1);
+    fs.utimesSync(b, mtime2, mtime2);
+
+    var util = require('../../src/util');
+    var actual = util.isStale(a, b);
+    t.equal(actual, false);
+    actual = util.isStale(b, a);
+    t.equal(actual, true);
+});
+