diff --git a/cluster.js b/cluster.js
index 499e1568..1cf0c4fa 100755
--- a/cluster.js
+++ b/cluster.js
@@ -11,9 +11,9 @@ var cluster = require('cluster');
 
 // sanity check
 var ENV = process.argv[2]
-if (ENV != 'development' && ENV != 'production'){
+if (ENV != 'development' && ENV != 'production' && ENV != 'staging'){
     console.error("\nnode app.js [environment]");
-    console.error("environments: [development, production]\n");
+    console.error("environments: [development, production, staging]\n");
     process.exit(1);
 }