diff --git a/i18n/__tests__/locale-resolution.test.ts b/i18n/__tests__/locale-resolution.test.ts
new file mode 100644
index 000000000..d44257bc3
--- /dev/null
+++ b/i18n/__tests__/locale-resolution.test.ts
@@ -0,0 +1,39 @@
+import { afterEach, describe, expect, it } from 'vitest';
+import { detectBrowserLocale } from '../detect-locale';
+import { localeFromAcceptLanguage, normalizeLocaleTag } from '../locale-resolution';
+
+const originalLanguages = Object.getOwnPropertyDescriptor(navigator, 'languages');
+
+function setBrowserLanguages(languages: string[]) {
+  Object.defineProperty(navigator, 'languages', {
+    configurable: true,
+    value: languages,
+  });
+}
+
+afterEach(() => {
+  if (originalLanguages) {
+    Object.defineProperty(navigator, 'languages', originalLanguages);
+  } else {
+    Reflect.deleteProperty(navigator, 'languages');
+  }
+});
+
+describe('Norwegian locale aliases', () => {
+  it.each(['no', 'no-NO'])('normalizes %s to Bokmål', (tag) => {
+    expect(normalizeLocaleTag(tag)).toBe('nb');
+  });
+
+  it('keeps native Bokmål tags on nb', () => {
+    expect(normalizeLocaleTag('nb-NO')).toBe('nb');
+  });
+
+  it('resolves no-NO from Accept-Language using quality ranking', () => {
+    expect(localeFromAcceptLanguage('da;q=0.5, no-NO;q=0.9, en;q=0.8')).toBe('nb');
+  });
+
+  it.each(['no', 'no-NO'])('detects browser language %s as Bokmål', (tag) => {
+    setBrowserLanguages([tag]);
+    expect(detectBrowserLocale('en')).toBe('nb');
+  });
+});
diff --git a/i18n/detect-locale.ts b/i18n/detect-locale.ts
index a20335847..5ee759a03 100644
--- a/i18n/detect-locale.ts
+++ b/i18n/detect-locale.ts
@@ -1,5 +1,6 @@
 import { routing } from './routing';
 import { useLocaleStore } from '@/stores/locale-store';
+import { normalizeLocaleTag } from './locale-resolution';
 
 /**
  * Pick the best supported locale for a first-time visitor from their browser
@@ -15,7 +16,7 @@ export function detectBrowserLocale(fallback: string): string {
   const prefs = navigator.languages?.length ? navigator.languages : [navigator.language];
   for (const tag of prefs) {
     if (!tag) continue;
-    const base = tag.toLowerCase().split('-')[0];
+    const base = normalizeLocaleTag(tag);
     if (base === 'en') return fallback;    // English is the top preference -> keep default
     if (supported.has(base)) return base;  // first supported non-English preference wins
   }
diff --git a/i18n/locale-resolution.ts b/i18n/locale-resolution.ts
new file mode 100644
index 000000000..4a53dfeb9
--- /dev/null
+++ b/i18n/locale-resolution.ts
@@ -0,0 +1,25 @@
+import { routing } from './routing';
+
+/** Map a BCP 47 language tag to the locale code Bulwark supports. */
+export function normalizeLocaleTag(tag: string): string {
+  const base = tag.trim().toLowerCase().split('-')[0];
+  return base === 'no' ? 'nb' : base;
+}
+
+/** Pick the highest-ranked supported locale from an Accept-Language header. */
+export function localeFromAcceptLanguage(header: string | null): string | null {
+  if (!header) return null;
+  const supported = new Set<string>(routing.locales as readonly string[]);
+  const ranked = header
+    .split(',')
+    .map((part) => {
+      const [tag, q] = part.trim().split(';q=');
+      return { locale: normalizeLocaleTag(tag), q: q ? parseFloat(q) : 1 };
+    })
+    .sort((a, b) => b.q - a.q);
+
+  for (const { locale } of ranked) {
+    if (supported.has(locale)) return locale;
+  }
+  return null;
+}
diff --git a/i18n/request.ts b/i18n/request.ts
index 59f3b3258..2986fa30c 100644
--- a/i18n/request.ts
+++ b/i18n/request.ts
@@ -1,29 +1,12 @@
 import { getRequestConfig } from 'next-intl/server';
 import { headers } from 'next/headers';
+import { localeFromAcceptLanguage, normalizeLocaleTag } from './locale-resolution';
 import { mergeMessages } from './merge-messages';
 import { routing, type Locale } from './routing';
 
-// Default a first-time visitor (no explicit stored choice) to the best supported
-// language from their browser's Accept-Language header, so "Auto" is the real
-// default and the first server render already matches the browser language.
-function localeFromAcceptLanguage(header: string | null): string | null {
-  if (!header) return null;
-  const supported = new Set<string>(routing.locales as readonly string[]);
-  const ranked = header
-    .split(',')
-    .map((part) => {
-      const [tag, q] = part.trim().split(';q=');
-      return { base: tag.toLowerCase().split('-')[0], q: q ? parseFloat(q) : 1 };
-    })
-    .sort((a, b) => b.q - a.q);
-  for (const { base } of ranked) {
-    if (supported.has(base)) return base;
-  }
-  return null;
-}
-
 export default getRequestConfig(async ({ requestLocale }) => {
   let locale = await requestLocale;
+  if (locale) locale = normalizeLocaleTag(locale);
 
   if (!locale || !routing.locales.includes(locale as Locale)) {
     const accept = (await headers()).get('accept-language');