diff --git a/README.md b/README.md
index 6e863aa..2cb00ef 100644
--- a/README.md
+++ b/README.md
@@ -34,7 +34,4 @@ jobs:
           asset_name: myapp_windows-nightly-$$.zip # name to upload the release as, use $$ to insert date (YYYYMMDD) and 6 letter commit hash
           asset_content_type: application/zip # required by GitHub API
           max_releases: 7 # optional, if there are more releases than this matching the asset_name, the oldest ones are going to be deleted
-          token: *** # optional, a github token. defaults to GITHUB_TOKEN
-          sha: 547fdf5 # optional, a commit SHA. Defaults to GITHUB_SHA
-          repo: Pure-D/serve-d # optional, the repository where the release is located
 ```
diff --git a/action.yml b/action.yml
index c79499c..1b665c5 100644
--- a/action.yml
+++ b/action.yml
@@ -26,18 +26,6 @@ inputs:
     description: 'Maximum number of historical releases with the given asset_name to keep'
     required: false
     default: 7
-  token:
-    description: 'The Github token.'
-    required: false
-    default: ${{ github.token }}
-  repo:
-    description: "Optionally specify the repo where the release is located. Defaults to current repo"
-    required: false
-    default: ${{ github.repository }}
-  sha:
-    description: "Optionally specify the commit SHA. Defaults to SHA that triggered the workflow"
-    required: false
-    default: ${{ github.sha }}
 
 output:
   uploaded:
diff --git a/index.js b/index.js
index 1362829..dd0ec63 100644
--- a/index.js
+++ b/index.js
@@ -35,21 +35,23 @@ async function uploadAsset(octokit, name) {
 
 async function run() {
 	try {
-		const token = core.getInput("token", { required: false });
-		const sha = core.getInput("sha", { required: false });
-		let repo = core.getInput("repo", { required: false });
 		const maxReleases = parseInt(core.getInput("max_releases", { required: false }));
 		const releaseId = core.getInput("release_id", { required: true });
 		let name = core.getInput("asset_name", { required: true });
 		const placeholderStart = name.indexOf("$$");
 		const nameStart = name.substring(0, placeholderStart);
 		const nameEnd = name.substring(placeholderStart + 2);
-		
-		const octokit = getOctokit(token);
-		const hash = sha.substring(0, 6);
-		const repository = repo.split('/');
+
+		if (!process.env.GITHUB_TOKEN
+			|| !process.env.GITHUB_SHA
+			|| !process.env.GITHUB_REPOSITORY)
+			throw new Error("Missing required GitHub environment variables!");
+
+		const octokit = getOctokit(process.env.GITHUB_TOKEN);
+		const hash = process.env.GITHUB_SHA.substring(0, 6);
+		const repository = process.env.GITHUB_REPOSITORY.split('/');
 		const owner = repository[0];
-		repo = repository[1];
+		const repo = repository[1];
 
 		core.info("Checking previous assets");
 		let assets = await octokit.rest.repos.listReleaseAssets({