diff --git a/package.json b/package.json
index 1e84516..a60e373 100644
--- a/package.json
+++ b/package.json
@@ -52,7 +52,7 @@
   "devDependencies": {
     "bluebird": "2",
     "mocha": "2",
-    "istanbul": "0"
+    "istanbul": "0.4.2"
   },
   "scripts": {
     "bench": "DEBUG=*:profile node benchmarks/mocha",