diff --git a/package.json b/package.json
index 8abf5e8c..e1a07dd1 100644
--- a/package.json
+++ b/package.json
@@ -29,6 +29,6 @@
     "typescript": "^1.8.7"
   },
   "dependencies": {
-    "pxt-core": "0.4.18"
+    "pxt-core": "0.4.21"
   }
 }