diff --git a/package.json b/package.json
index 4b2aaf2..5e90cb6 100644
--- a/package.json
+++ b/package.json
@@ -7,7 +7,7 @@
     "webpack": ">=0.11 <2"
   },
   "dependencies": {
-    "async": "0.2.x"
+    "async": "0.9.2"
   },
   "optionalDependencies": {
     "node-zopfli": "^1.3.4"