diff --git a/package.json b/package.json
index 2419298..ccfe439 100644
--- a/package.json
+++ b/package.json
@@ -22,7 +22,7 @@
   },
   "homepage": "https://github.com/T-PWK/node-line-reader",
   "devDependencies": {
-    "async": "^0.9.0"
+    "async": "^2.6.4"
   },
   "engines": {
     "node": ">=0.10"
diff --git a/yarn.lock b/yarn.lock
index 83f3243..3ba3035 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2,6 +2,12 @@
 # yarn lockfile v1
 
 
-async@^0.9.0:
-  version "0.9.2"
-  resolved "https://registry.yarnpkg.com/async/-/async-0.9.2.tgz#aea74d5e61c1f899613bf64bda66d4c78f2fd17d"
+async@^2.6.4:
+  version "2.6.4"
+  resolved "https://registry.yarnpkg.com/async/-/async-2.6.4.tgz#706b7ff6084664cd7eae713f6f965433b5504221"
+  dependencies:
+    lodash "^4.17.14"
+
+lodash@^4.17.14:
+  version "4.17.21"
+  resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.21.tgz#679591c564c3bffaae8454cf0b3df370c3d6911c"