diff --git a/lib/output/json.js b/lib/output/json.js
index 86a230758..e8a71cc28 100644
--- a/lib/output/json.js
+++ b/lib/output/json.js
@@ -21,6 +21,9 @@ JSONOutput.prototype.onPage = function(page) {
         // Delete some private properties
         delete json.config;
 
+        // Specify JSON output version
+        json.version = '2';
+
         return that.writeFile(
             page.withExtension('.json'),
             JSON.stringify(json, null, 4)