diff --git a/lib/find.js b/lib/find.js
index e520ce8..34bd310 100644
--- a/lib/find.js
+++ b/lib/find.js
@@ -1,7 +1,7 @@
 const is = require('./is.js')
-const { dirname, sep } = require('path')
+const { dirname } = require('path')
 
-module.exports = async ({ cwd = process.cwd(), root = sep } = {}) => {
+module.exports = async ({ cwd = process.cwd(), root } = {}) => {
   while (true) {
     if (await is({ cwd })) {
       return cwd
diff --git a/test/find.js b/test/find.js
index 3101912..1951cc4 100644
--- a/test/find.js
+++ b/test/find.js
@@ -1,5 +1,6 @@
 const t = require('tap')
-const { join } = require('path')
+const { join, parse } = require('path')
+const { tmpdir } = require('os')
 const find = require('../lib/find.js')
 
 t.test('find the git dir many folders up', t => {
@@ -7,8 +8,7 @@ t.test('find the git dir many folders up', t => {
     '.git': { index: 'hello' },
     a: { b: { c: { d: { e: {} } } } },
   })
-  const path = `${root}/a/b/c/d/e`
-  return t.resolveMatch(find({ cwd: path }), root)
+  return t.resolveMatch(find({ cwd: join(root, 'a/b/c/d/e') }), root)
 })
 
 t.test('stop before root dir', t => {
@@ -16,8 +16,7 @@ t.test('stop before root dir', t => {
     '.git': { index: 'hello' },
     a: { b: { c: { d: { e: {} } } } },
   })
-  const path = `${root}/a/b/c/d/e`
-  return t.resolveMatch(find({ cwd: path, root: join(root, 'a') }), null)
+  return t.resolveMatch(find({ cwd: join(root, 'a/b/c/d/e'), root: join(root, 'a') }), null)
 })
 
 t.test('stop at root dir', t => {
@@ -25,8 +24,7 @@ t.test('stop at root dir', t => {
     '.git': { index: 'hello' },
     a: { b: { c: { d: { e: {} } } } },
   })
-  const path = `${root}/a/b/c/d/e`
-  return t.resolveMatch(find({ cwd: path, root }), root)
+  return t.resolveMatch(find({ cwd: join(root, 'a/b/c/d/e'), root }), root)
 })
 
 t.test('find the git dir at current level', t => {
@@ -38,13 +36,35 @@ t.test('find the git dir at current level', t => {
 
 t.test('no git dir to find', t => {
   // this will fail if your tmpdir is in a git repo, I suppose
-  const path = require('os').tmpdir()
-  return t.resolveMatch(find({ cwd: path }), null)
+  return t.resolveMatch(find({ cwd: tmpdir() }), null)
 })
 
 t.test('default to cwd', t => {
-  // this will fail if your tmpdir is in a git repo, I suppose
-  const path = require('os').tmpdir()
-  process.chdir(path)
+  const dir = process.cwd()
+  t.teardown(() => process.chdir(dir))
+  process.chdir(tmpdir())
   return t.resolveMatch(find(), null)
 })
+
+t.test('mock is', async t => {
+  const cwd = tmpdir()
+  const { root } = parse(cwd)
+
+  const mockFind = async (t, opts) => {
+    const seen = []
+    const mocked = t.mock('../lib/find.js', {
+      '../lib/is.js': async (o) => {
+        seen.push(o.cwd)
+        return false
+      },
+    })
+    const res = await mocked({ cwd, ...opts })
+    t.strictSame(res, null)
+    t.strictSame(seen, [...new Set(seen)], 'no directory checked more than once')
+    t.equal(seen[seen.length - 1], root, 'last dir is root')
+  }
+
+  for (const tCase of [undefined, { root }, { root: 1 }]) {
+    await t.test(`root: ${JSON.stringify(tCase)}`, t => mockFind(t, tCase))
+  }
+})