diff --git a/package.json b/package.json
index 5ef761e..c18a8f9 100644
--- a/package.json
+++ b/package.json
@@ -21,7 +21,7 @@
   },
   "devDependencies": {
     "babel-cli": "6",
-    "babel-core": "6",
+    "babel-core": "6.3.26",
     "babel-preset-es2015": "6",
     "benchmark": "1",
     "finalhandler": "0",