diff --git a/‎packages/mocker/src/browser/mocker.ts‎
Lines changed: 3 additions & 2 deletions b/‎packages/mocker/src/browser/mocker.ts‎
Lines changed: 3 additions & 2 deletions
diff --git a/‎test/browser/fixtures/mocking-out-of-root/project1-utils/index.js‎
Lines changed: 1 addition & 0 deletions b/‎test/browser/fixtures/mocking-out-of-root/project1-utils/index.js‎
Lines changed: 1 addition & 0 deletions
diff --git a/‎test/browser/fixtures/mocking-out-of-root/project1/basic.test.js‎
Lines changed: 9 additions & 0 deletions b/‎test/browser/fixtures/mocking-out-of-root/project1/basic.test.js‎
Lines changed: 9 additions & 0 deletions
@@ -2,6 +2,7 @@ import type { CreateMockInstanceProcedure } from '../automocker'
 import type { MockedModule, MockedModuleType } from '../registry'
 import type { ModuleMockContext, ModuleMockOptions, TestModuleMocker } from '../types'
 import type { ModuleMockerInterceptor } from './interceptor'
+import { withTrailingSlash } from '@vitest/utils/helpers'
 import { extname, join } from 'pathe'
 import { mockObject } from '../automocker'
 import { AutomockedModule, MockerRegistry, RedirectedModule } from '../registry'
@@ -277,11 +278,11 @@ export class ModuleMocker implements TestModuleMocker {
     const fsRoot = join('/@fs/', config.root)
 
     // URL can be /file/path.js, but path is resolved to /file/path
-    if (path.startsWith(config.root)) {
+    if (path.startsWith(withTrailingSlash(config.root))) {
       return path.slice(config.root.length)
     }
 
-    if (path.startsWith(fsRoot)) {
+    if (path.startsWith(withTrailingSlash(fsRoot))) {
       return path.slice(fsRoot.length)
     }
 
 
@@ -0,0 +1 @@
+export default "project1-utils"
@@ -1,12 +1,21 @@
 import { test, expect, vi } from 'vitest';
 import project2 from "../project2/index.js"
+import project1Utils from "../project1-utils/index.js"
 import "./imported-test.js"
 import "../project3/imported-test.js"
 
 vi.mock("../project2/index.js", () => ({
   default: 'project2-mocked'
 }))
 
+vi.mock("../project1-utils/index.js", () => ({
+  default: 'project1-utils-mocked'
+}))
+
 test("basic", () => {
   expect(project2).toMatchInlineSnapshot(`"project2-mocked"`)
 })
+
+test("sibling directory that shares the root prefix", () => {
+  expect(project1Utils).toMatchInlineSnapshot(`"project1-utils-mocked"`)
+})