--- a/intl/locale/nsLanguageAtomService.cpp
+++ b/intl/locale/nsLanguageAtomService.cpp
@@ -4,22 +4,22 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "nsLanguageAtomService.h"
 #include "nsUConvPropertySearch.h"
 #include "nsUnicharUtils.h"
 #include "nsIAtom.h"
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/Services.h"
-#include "mozilla/intl/LocaleService.h"
+#include "mozilla/intl/OSPreferences.h"
 #include "nsServiceManagerUtils.h"
 #include "mozilla/dom/EncodingUtils.h"
 
 using namespace mozilla;
-using mozilla::intl::LocaleService;
+using mozilla::intl::OSPreferences;
 
 static constexpr nsUConvProp kLangGroups[] = {
 #include "langGroups.properties.h"
 };
 
 NS_IMPL_ISUPPORTS(nsLanguageAtomService, nsILanguageAtomService)
 
 nsLanguageAtomService::nsLanguageAtomService()
@@ -46,17 +46,17 @@ nsLanguageAtomService::LookupCharSet(con
 }
 
 nsIAtom*
 nsLanguageAtomService::GetLocaleLanguage()
 {
   do {
     if (!mLocaleLanguage) {
       nsAutoCString locale;
-      LocaleService::GetInstance()->GetAppLocaleAsLangTag(locale);
+      OSPreferences::GetInstance()->GetSystemLocale(locale);
 
       ToLowerCase(locale); // use lowercase for all language atoms
       mLocaleLanguage = NS_Atomize(locale);
     }
   } while (0);
 
   return mLocaleLanguage;
 }