diff --git a/lib/lock-worker.js b/lib/lock-worker.js
index 864e34f..aa408f6 100644
--- a/lib/lock-worker.js
+++ b/lib/lock-worker.js
@@ -33,7 +33,7 @@ async function main (cache, integrity, pkg, opts) {
   opts.log.notice('fs', 'fetching', `${pkg.name}@${pkg.version}`)
   try {
     if (!prepare) { prepare = require('./commands/prepare.js') }
-    const res = await prepare([pkg.name], opts)
+    const res = await prepare({packages: [pkg.name]}, opts)
     if (res && !res.pkgCount) { throw new Error('no packages installed') }
   } catch (err) {
     if (!ensurePkg) { ensurePkg = require('./ensure-package.js') }