diff --git a/examples/mocks/__mocks__/extension.js.ts b/examples/mocks/__mocks__/extension.js.ts
new file mode 100644
index 000000000..879c9bbb6
--- /dev/null
+++ b/examples/mocks/__mocks__/extension.js.ts
@@ -0,0 +1 @@
+export const mocked = true
diff --git a/examples/mocks/test/has-extension.spec.ts b/examples/mocks/test/has-extension.spec.ts
new file mode 100644
index 000000000..3b26b04a1
--- /dev/null
+++ b/examples/mocks/test/has-extension.spec.ts
@@ -0,0 +1,8 @@
+// @ts-expect-error mocked module
+import { mocked } from 'extension.js'
+
+vi.mock('extension.js')
+
+test('module with extension is mocked', () => {
+  expect(mocked).toBe(true)
+})
diff --git a/packages/vitest/src/runtime/mocker.ts b/packages/vitest/src/runtime/mocker.ts
index 039811775..33c5c8355 100644
--- a/packages/vitest/src/runtime/mocker.ts
+++ b/packages/vitest/src/runtime/mocker.ts
@@ -1,6 +1,6 @@
 import { existsSync, readdirSync } from 'fs'
 import { isNodeBuiltin } from 'mlly'
-import { basename, dirname, join, resolve } from 'pathe'
+import { basename, dirname, extname, join, resolve } from 'pathe'
 import { normalizeRequestId, pathFromRoot, toFilePath } from 'vite-node/utils'
 import type { ModuleCacheMap } from 'vite-node/client'
 import { getAllMockableProperties, getType, getWorkerState, mergeSlashes, slash } from '../utils'
@@ -165,11 +165,11 @@ export class VitestMocker {
         return null
 
       const files = readdirSync(mockFolder)
-      const baseFilename = basename(path)
+      const baseOriginal = basename(path)
 
       for (const file of files) {
-        const [basename] = file.split('.')
-        if (basename === baseFilename)
+        const baseFile = basename(file, extname(file))
+        if (baseFile === baseOriginal)
           return resolve(mockFolder, file)
       }