diff --git a/package.json b/package.json
index de5933f9a8..f2b6faaa83 100644
--- a/package.json
+++ b/package.json
@@ -46,8 +46,9 @@
     "regenerator": "0.6.7",
     "chokidar": "0.10.0",
     "source-map-support": "0.2.7",
-    "acorn": "0.9.0",
-    "ast-types": "0.5.3"
+    "ast-types": "0.5.3",
+    "esutils": "^1.1.4",
+    "acorn": "^0.9.0"
   },
   "devDependencies": {
     "istanbul": "0.3.2",