diff --git a/package.json b/package.json
index f59416e..bdc67cf 100644
--- a/package.json
+++ b/package.json
@@ -11,7 +11,7 @@
   },
   "devDependencies": {
     "bluebird": "^2.3.4",
-    "istanbul": "0",
+    "istanbul": "0.4.2",
     "mocha": "1",
     "polyfills": "^1.5.0",
     "spdy": "^1.28.1",