diff --git a/src/package-manifest.test.ts b/src/package-manifest.test.ts
index 98078c7..06e30c6 100644
--- a/src/package-manifest.test.ts
+++ b/src/package-manifest.test.ts
@@ -13,6 +13,8 @@ function getPackedPaths() {
   const output = execFileSync("npm", ["pack", "--dry-run", "--json"], {
     cwd: packageRoot,
     encoding: "utf8",
+    timeout: 30_000,
+    stdio: ["ignore", "pipe", "pipe"],
   });
   const [packResult] = JSON.parse(output) as Array<{ files: Array<{ path: string }> }>;
   return packResult.files.map((file) => file.path);
@@ -60,5 +62,5 @@ test("npm pack includes runtime package assets", () => {
   assert.ok(packedPaths.includes("src/runtime.ts"));
 
   // Ensure no test source files are included in npm pack
-  assert.ok(!packedPaths.some((p) => p.endsWith(".test.ts")));
+  assert.deepEqual(packedPaths.filter((p) => p.endsWith(".test.ts")), []);
 });