diff --git a/README.md b/README.md
index 56e78db..5c41823 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,9 @@
 # 🦪 zx-extra
 [zx](https://github.com/google/zx) with some extras
 
+## Requirements
+* Node.js >= 16.0.0
+
 ## Install
 ```shell
 # npm
@@ -65,7 +68,7 @@ const output = (await $.raw`${cmd} ${msg}`).toString().trim()
 ```
 
 ### `$.opt`
-Returns `$` with the specified preset.
+Returns `$` with the specified preset. Aliased for `$.o`.
 ```js
 const $$ = $.opt({verbose: false, spawn: customSpawn})
 
diff --git a/src/main/js/index.d.ts b/src/main/js/index.d.ts
index ff8e1e0..86e6200 100644
--- a/src/main/js/index.d.ts
+++ b/src/main/js/index.d.ts
@@ -17,6 +17,7 @@ interface $ {
   silent: $
   preferLocal?: boolean
   opt: (options: any) => $
+  o: (options: any) => $
 }
 
 export function createHook(opts?: $, name?: string, cb?: (p: ProcessPromise) => any, configurable?: boolean)