diff --git a/action.yaml b/action.yaml
index de85be4..78d8ae1 100644
--- a/action.yaml
+++ b/action.yaml
@@ -15,6 +15,7 @@ inputs:
   ref:
     description: "The reference can be a branch, tag, or a commit SHA"
     required: false
+    default: ${{ github.head_ref || github.ref }}
   repo:
     description: "Repo owner & name, slash separated, only set if invoking a workflow in a different repo"
     required: false
diff --git a/src/main.ts b/src/main.ts
index c78c4df..67c7693 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -26,7 +26,7 @@ async function run(): Promise<void> {
 
     // Optional inputs, with defaults
     const token = core.getInput('token')
-    const ref = core.getInput('ref') || github.context.ref
+    const ref = core.getInput('ref')
     const [owner, repo] = core.getInput('repo')
       ? core.getInput('repo').split('/')
       : [github.context.repo.owner, github.context.repo.repo]