diff --git a/.changeset/lazy-hounds-tan.md b/.changeset/lazy-hounds-tan.md
new file mode 100644
index 0000000000..87071abf9e
--- /dev/null
+++ b/.changeset/lazy-hounds-tan.md
@@ -0,0 +1,6 @@
+---
+'nextra': patch
+'nextra-theme-docs': patch
+---
+
+fix(nextra/docs): fallback search to `en-US` instead `default`
diff --git a/packages/nextra-theme-docs/src/flexsearch.js b/packages/nextra-theme-docs/src/flexsearch.js
index 0db270a94f..93581738e5 100644
--- a/packages/nextra-theme-docs/src/flexsearch.js
+++ b/packages/nextra-theme-docs/src/flexsearch.js
@@ -6,7 +6,7 @@ import React, {
   useEffect,
   Fragment
 } from 'react'
-import Router, { useRouter } from 'next/router'
+import { useRouter } from 'next/router'
 import cn from 'classnames'
 import Link from 'next/link'
 import FlexSearch from 'flexsearch'
@@ -34,7 +34,7 @@ const Item = ({
           {page}
         </div>
       ) : null}
-      <Link href={Router.basePath + href}>
+      <Link href={href}>
         <a
           className="block no-underline"
           onMouseMove={onHover}
@@ -113,7 +113,7 @@ export default function Search() {
   const doSearch = () => {
     if (!search) return
 
-    const localeCode = Router.locale || 'default'
+    const localeCode = router.locale
     const index = indexes[localeCode]
 
     if (!index) return
@@ -251,11 +251,11 @@ export default function Search() {
   )
 
   const load = async () => {
-    const localeCode = Router.locale || 'default'
+    const localeCode = router.locale
     if (!indexes[localeCode] && !loading) {
       setLoading(true)
       const response = await fetch(
-        `${Router.basePath}/_next/static/chunks/nextra-data-${localeCode}.json`
+        `${router.basePath}/_next/static/chunks/nextra-data-${localeCode}.json`
       )
       const data = await response.json()
 
@@ -430,7 +430,7 @@ export default function Search() {
                   key={`search-item-${i}`}
                   page={res.page}
                   title={res.title}
-                  href={res.route}
+                  href={router.basePath + res.route}
                   excerpt={res.excerpt}
                   active={i === active}
                   onHover={() => setActive(i)}
diff --git a/packages/nextra/src/constants.ts b/packages/nextra/src/constants.ts
index 1054286461..2857b72603 100644
--- a/packages/nextra/src/constants.ts
+++ b/packages/nextra/src/constants.ts
@@ -3,3 +3,5 @@ export const MARKDOWN_EXTENSION_REGEX = /\.mdx?$/
 export const IS_PRODUCTION = process.env.NODE_ENV === 'production'
 
 export const LOCALE_REGEX = /\.([a-z]{2}(-[A-Z]{2})?)$/
+
+export const DEFAULT_LOCALE = 'en-US'
diff --git a/packages/nextra/src/index.ts b/packages/nextra/src/index.ts
index 931671a5d9..2558ad9939 100644
--- a/packages/nextra/src/index.ts
+++ b/packages/nextra/src/index.ts
@@ -1,5 +1,5 @@
 import { NextraPlugin, pageMapCache } from './plugin'
-import { MARKDOWN_EXTENSION_REGEX } from './constants'
+import { DEFAULT_LOCALE, MARKDOWN_EXTENSION_REGEX } from './constants'
 import { LoaderOptions, Nextra } from './types'
 
 const DEFAULT_EXTENSIONS = ['js', 'jsx', 'ts', 'tsx'] as const
@@ -25,12 +25,12 @@ const nextra: Nextra = (...args) =>
     } else if (!i18n?.defaultLocale) {
       // If `i18n.locales` and `i18n.defaultLocale` were not specified,
       // client will receive error - Text content does not match server-rendered HTML.
-      // Due to `const { locales } = useRouter()` where `locales` will be `undefined`
+      // Due to `const { locale } = useRouter()` where `locale` will be `undefined`
       // To fix it we need to explicitly specify `i18n.locales` and `i18n.defaultLocale`
       nextConfig.i18n = {
         ...i18n,
-        locales: ['en-US'],
-        defaultLocale: 'en-US'
+        locales: [DEFAULT_LOCALE],
+        defaultLocale: DEFAULT_LOCALE
       }
     }
 
diff --git a/packages/nextra/src/loader.ts b/packages/nextra/src/loader.ts
index d8813c3c0a..66624ce9e4 100644
--- a/packages/nextra/src/loader.ts
+++ b/packages/nextra/src/loader.ts
@@ -11,7 +11,7 @@ import { parseFileName } from './utils'
 import { compileMdx } from './compile'
 import { getPageMap, findPagesDir } from './page-map'
 import { collectFiles, collectMdx } from './plugin'
-import { MARKDOWN_EXTENSION_REGEX, IS_PRODUCTION } from './constants'
+import { MARKDOWN_EXTENSION_REGEX, IS_PRODUCTION, DEFAULT_LOCALE } from './constants'
 
 // TODO: create this as a webpack plugin.
 const indexContentEmitted = new Set<string>()
@@ -130,7 +130,7 @@ async function loader(
     // We only add .MD and .MDX contents
     if (MARKDOWN_EXTENSION_REGEX.test(filename) && data.searchable !== false) {
       addPage({
-        fileLocale: fileLocale || 'default',
+        fileLocale: fileLocale || DEFAULT_LOCALE,
         route,
         title,
         data,