diff --git a/README.md b/README.md
index 41a1433..0d73252 100644
--- a/README.md
+++ b/README.md
@@ -64,7 +64,7 @@ Input and output changes:
 
 Version of pnpm to install.
 
-**Optional** when there is a [`packageManager` or `devEngines.packageManager` field in the `package.json`](https://nodejs.org/api/corepack.html).
+**Optional** when `package.json` declares pnpm in `packageManager`, or sets `devEngines.packageManager.name` to `"pnpm"` and provides `devEngines.packageManager.version`.
 
 otherwise, this field is **required** It supports npm versioning scheme, it could be an exact version (such as `10.9.8`), or a version range (such as `10`, `10.x.x`, `10.9.x`, `^10.9.8`, `*`, etc.), or `latest`.
 
@@ -157,6 +157,8 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
+      - uses: actions/checkout@v6
+
       - uses: pnpm/action-setup@v6
 ```