diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index e95a766dc716b..4afa69eb2e251 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -695,10 +695,10 @@ npm run dev-server
 npm run dev-server -- --port=9001
 
 # Proxy backend requests to a Flask server running on a non-default port
-npm run dev-server -- --supersetPort=8081
+npm run dev-server -- --env=--supersetPort=8081
 
 # Proxy to a remote backend but serve local assets
-npm run dev-server -- --superset=https://superset-dev.example.com
+npm run dev-server -- --env=--superset=https://superset-dev.example.com
 ```
 
 The `--superset=` option is useful in case you want to debug a production issue or have to setup Superset behind a firewall. It allows you to run Flask server in another environment while keep assets building locally for the best developer experience.
diff --git a/superset-frontend/webpack.proxy-config.js b/superset-frontend/webpack.proxy-config.js
index ebac6899455c9..29823144d4e9e 100644
--- a/superset-frontend/webpack.proxy-config.js
+++ b/superset-frontend/webpack.proxy-config.js
@@ -18,10 +18,18 @@
  */
 const zlib = require('zlib');
 
+const yargs = require('yargs');
 // eslint-disable-next-line import/no-extraneous-dependencies
-const parsedArgs = require('yargs').argv;
+const parsedArgs = yargs.argv;
 
-const { supersetPort = 8088, superset: supersetUrl = null } = parsedArgs;
+const parsedEnvArg = () => {
+  if (parsedArgs.env) {
+    return yargs(parsedArgs.env).argv;
+  }
+  return {};
+};
+
+const { supersetPort = 8088, superset: supersetUrl = null } = parsedEnvArg();
 const backend = (supersetUrl || `http://localhost:${supersetPort}`).replace(
   '//+$/',
   '',