diff --git a/coretool.js b/coretool.js
index 71d850c..ce57c21 100644
--- a/coretool.js
+++ b/coretool.js
@@ -13,7 +13,7 @@ module.exports = {
     try {
       return JSON.parse(value)
     } catch (e) {
-      return value
+      return undefined
     }
   },