diff --git a/package.json b/package.json
index ed9b52f..30ecd49 100644
--- a/package.json
+++ b/package.json
@@ -33,7 +33,7 @@
   "devDependencies": {
     "assert": "*",
     "babel-cli": "*",
-    "babel-core": "*",
+    "babel-core": "6.10.4",
     "babel-preset-es2015": "*",
     "coveralls": "*",
     "isparta": "*",