diff --git a/test/cli.subprocess.test.ts b/test/cli.subprocess.test.ts
index 959f212..97ddece 100644
--- a/test/cli.subprocess.test.ts
+++ b/test/cli.subprocess.test.ts
@@ -7,7 +7,7 @@
  * and runs `auth whoami` against the mock."
  */
 
-import { execFileSync, spawn } from 'node:child_process';
+import { spawn } from 'node:child_process';
 import { existsSync, mkdtempSync, rmSync, statSync } from 'node:fs';
 import type { IncomingMessage, Server, ServerResponse } from 'node:http';
 import { createServer } from 'node:http';
@@ -15,6 +15,7 @@ import { tmpdir } from 'node:os';
 import { dirname, join, resolve } from 'node:path';
 import { fileURLToPath } from 'node:url';
 import { afterAll, beforeAll, describe, expect, it } from 'vitest';
+import { runNpmScript } from './helpers/npm.js';
 
 const __dirname = dirname(fileURLToPath(import.meta.url));
 const REPO_ROOT = resolve(__dirname, '..');
@@ -37,7 +38,7 @@ beforeAll(async () => {
   // existsSync skip we used to do here let `dist` rot under
   // refactors and gave false-green on `project list` once
   // already.
-  execFileSync('npm', ['run', 'build'], { cwd: REPO_ROOT, stdio: 'pipe' });
+  runNpmScript('build', REPO_ROOT);
   server = createServer((req: IncomingMessage, res: ServerResponse) => {
     const url = req.url ?? '/';
     if (url.startsWith('/api/cli/v1/projects/')) {
diff --git a/test/help.snapshot.test.ts b/test/help.snapshot.test.ts
index ee89b3b..79b150b 100644
--- a/test/help.snapshot.test.ts
+++ b/test/help.snapshot.test.ts
@@ -13,6 +13,7 @@ import { execFileSync } from 'node:child_process';
 import { dirname, join, resolve } from 'node:path';
 import { fileURLToPath } from 'node:url';
 import { beforeAll, describe, expect, it } from 'vitest';
+import { runNpmScript } from './helpers/npm.js';
 
 const __dirname = dirname(fileURLToPath(import.meta.url));
 const REPO_ROOT = resolve(__dirname, '..');
@@ -47,7 +48,7 @@ const cases: Array<[string, string[]]> = [
 
 describe('--help snapshots', () => {
   beforeAll(() => {
-    execFileSync('npm', ['run', 'build'], { cwd: REPO_ROOT, stdio: 'pipe' });
+    runNpmScript('build', REPO_ROOT);
   });
 
   for (const [name, args] of cases) {
diff --git a/test/helpers/npm.ts b/test/helpers/npm.ts
new file mode 100644
index 0000000..747405a
--- /dev/null
+++ b/test/helpers/npm.ts
@@ -0,0 +1,13 @@
+import { execFileSync } from 'node:child_process';
+
+export function runNpmScript(script: string, cwd: string): void {
+  const npmExecPath = process.env.npm_execpath;
+  if (npmExecPath) {
+    execFileSync(process.execPath, [npmExecPath, 'run', script], { cwd, stdio: 'pipe' });
+    return;
+  }
+  execFileSync(process.platform === 'win32' ? 'npm.cmd' : 'npm', ['run', script], {
+    cwd,
+    stdio: 'pipe',
+  });
+}