diff --git a/test/smoke/pack-smoke.mjs b/test/smoke/pack-smoke.mjs
index a7f3dbf..a1615a6 100644
--- a/test/smoke/pack-smoke.mjs
+++ b/test/smoke/pack-smoke.mjs
@@ -7,11 +7,17 @@ const repoRoot = resolve(new URL('../..', import.meta.url).pathname)
 const sandbox = mkdtempSync(join(tmpdir(), 'ocex-pack-smoke-'))
 
 try {
-  const packedName = execSync('npm pack --silent', {
+  const packedRaw = execSync('npm pack --json --silent', {
     cwd: repoRoot,
     encoding: 'utf8'
   }).trim()
 
+  const packed = JSON.parse(packedRaw)
+  const packedName = Array.isArray(packed) ? packed[0]?.filename : null
+  if (!packedName) {
+    throw new Error('npm pack did not return a tarball filename')
+  }
+
   const tarball = join(repoRoot, packedName)
   const probeDir = join(sandbox, 'probe')
   execSync('mkdir -p probe', { cwd: sandbox })