diff --git a/.github/workflows/expire.yml b/.github/workflows/expire.yml
index 6ee8a00..c51bb3d 100644
--- a/.github/workflows/expire.yml
+++ b/.github/workflows/expire.yml
@@ -102,7 +102,7 @@ jobs:
                 await github.rest.git.deleteRef({
                   owner: repoOwner,
                   repo: repoName,
-                  ref: 'heads/${pull['head']['ref']}',
+                  ref: `heads/${pull['head']['ref']}`,
                 });
               } else {
                 core.info(`Skipping #${pull['number']} (${pull['title']}) - not an AOD request`);