diff --git a/README.md b/README.md
index 099c851af..9c9432513 100644
--- a/README.md
+++ b/README.md
@@ -28,6 +28,8 @@ You can get our mobile versions from here:
 
 ## Building the sources
 
+Node.js >= 6 is required.
+
 On Debian/Ubuntu systems, the required packages can be installed with:
 ```
 sudo apt-get install npm nodejs-legacy
diff --git a/package.json b/package.json
index b95938613..226ec979a 100644
--- a/package.json
+++ b/package.json
@@ -98,6 +98,9 @@
     "webpack": "2.6.1",
     "webpack-dev-server": "2.4.5"
   },
+  "engines": {
+      "node": ">=6.0.0"
+  },
   "license": "Apache-2.0",
   "scripts": {
     "lint": "jshint . && eslint . && flow",