diff --git a/README.md b/README.md
index 29e2945..52659ef 100644
--- a/README.md
+++ b/README.md
@@ -350,11 +350,11 @@ And then export an async function from your module:
 
 ```javascript
 module.exports = async ({github, context, core}) => {
-  const {SHA} = process.env
+  const {GITHUB_SHA} = process.env
   const commit = await github.rest.repos.getCommit({
     owner: context.repo.owner,
     repo: context.repo.repo,
-    ref: `${SHA}`
+    ref: `${GITHUB_SHA}`
   })
   core.exportVariable('author', commit.data.commit.author.email)
 }