diff --git a/package.json b/package.json
index dddfef2..27fd09c 100644
--- a/package.json
+++ b/package.json
@@ -8,7 +8,7 @@
   "dependencies": {},
   "devDependencies": {
     "mocha": "2",
-    "istanbul": "0"
+    "istanbul": "0.4.2"
   },
   "scripts": {
     "test": "mocha --reporter spec",