diff --git a/HMCL/src/main/java/org/jackhuang/hmcl/util/i18n/Locales.java b/HMCL/src/main/java/org/jackhuang/hmcl/util/i18n/Locales.java
index 2333f462e..e0bfe99f8 100644
--- a/HMCL/src/main/java/org/jackhuang/hmcl/util/i18n/Locales.java
+++ b/HMCL/src/main/java/org/jackhuang/hmcl/util/i18n/Locales.java
@@ -142,9 +142,9 @@ public final class Locales {
             }
 
             Locale inJavaLocale = inLocale.getLocale();
-            if (LocaleUtils.isISO3Language(inJavaLocale.getLanguage())) {
+            if (inJavaLocale.getLanguage().length() > 2) {
                 String iso1 = LocaleUtils.getISO1Language(inJavaLocale);
-                if (LocaleUtils.isISO1Language(iso1)) {
+                if (iso1.length() <= 2) {
                     Locale.Builder builder = new Locale.Builder()
                             .setLocale(inJavaLocale)
                             .setLanguage(iso1);
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/i18n/DefaultResourceBundleControl.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/i18n/DefaultResourceBundleControl.java
index 8bfc484df..75d8880a9 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/i18n/DefaultResourceBundleControl.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/i18n/DefaultResourceBundleControl.java
@@ -30,7 +30,7 @@ import java.util.ResourceBundle;
 /// - For all Chinese locales, `zh-CN` is always added to the candidate list. If `zh-Hans` already exists in the candidate list,
 ///   `zh-CN` is inserted before `zh`; otherwise, it is inserted after `zh`.
 /// - For all Traditional Chinese locales, `zh-TW` is always added to the candidate list (before `zh`).
-/// - For all [supported][LocaleUtils#toISO1Language(String)] ISO 639-3 language code (such as `eng`, `zho`, `lzh`, etc.),
+/// - For all [supported][LocaleUtils#mapToISO1Language(String)] ISO 639-3 language code (such as `eng`, `zho`, `lzh`, etc.),
 ///  a candidate list with the language code replaced by the ISO 639-1 (Macro)language code is added to the end of the candidate list.
 ///
 /// @author Glavo
@@ -41,7 +41,6 @@ public class DefaultResourceBundleControl extends ResourceBundle.Control {
     public DefaultResourceBundleControl() {
     }
 
-
     @Override
     public List<Locale> getCandidateLocales(String baseName, Locale locale) {
         return LocaleUtils.getCandidateLocales(locale);
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/i18n/LocaleUtils.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/i18n/LocaleUtils.java
index 80c3e8c5c..9f0912994 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/i18n/LocaleUtils.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/i18n/LocaleUtils.java
@@ -64,18 +64,24 @@ public final class LocaleUtils {
                 : locale.stripExtensions().toLanguageTag();
     }
 
-    public static boolean isISO1Language(String language) {
-        return language.length() == 2;
-    }
-
-    public static boolean isISO3Language(String language) {
-        return language.length() == 3;
-    }
-
     public static @NotNull String getISO1Language(Locale locale) {
         String language = locale.getLanguage();
         if (language.isEmpty()) return "en";
-        return isISO3Language(language) ? toISO1Language(language) : language;
+        if (language.length() <= 2)
+            return language;
+
+        String lang = language;
+        while (lang != null) {
+            if (lang.length() <= 2)
+                return lang;
+            else {
+                String iso1 = mapToISO1Language(lang);
+                if (iso1 != null)
+                    return iso1;
+            }
+            lang = getParentLanguage(lang);
+        }
+        return language;
     }
 
     /// Get the script of the locale. If the script is empty and the language is Chinese,
@@ -288,6 +294,7 @@ public final class LocaleUtils {
 
     // ---
 
+    /// Map ISO 639-3 language codes to ISO 639-1 language codes.
     private static @Nullable String mapToISO1Language(String iso3Language) {
         return switch (iso3Language) {
             case "eng" -> "en";
@@ -309,23 +316,6 @@ public final class LocaleUtils {
         };
     }
 
-    /// Try to convert ISO 639-3 language codes to ISO 639-1 language codes.
-    public static String toISO1Language(String languageTag) {
-        String lang = languageTag;
-        while (lang != null) {
-            if (lang.length() <= 2)
-                return lang;
-            else {
-                String iso1 = mapToISO1Language(lang);
-                if (iso1 != null)
-                    return iso1;
-            }
-            lang = getParentLanguage(lang);
-        }
-
-        return languageTag;
-    }
-
     public static boolean isEnglish(Locale locale) {
         return "en".equals(getISO1Language(locale));
     }