diff --git a/app/Helpers/Helper.php b/app/Helpers/Helper.php
index c7aa5af04a..472281eca0 100644
--- a/app/Helpers/Helper.php
+++ b/app/Helpers/Helper.php
@@ -1317,7 +1317,7 @@ class Helper
 
 
     /*
-     * I know it's gauche  to return a shitty HTML string, but this is just a helper and since it will be the same every single time,
+     * I know it's gauche to return a shitty HTML string, but this is just a helper and since it will be the same every single time,
      * it seemed pretty safe to do here. Don't you judge me.
      */
     public static function showDemoModeFieldWarning() {
@@ -1325,4 +1325,86 @@ class Helper
             return "<p class=\"text-warning\"><i class=\"fas fa-lock\"></i>" . trans('general.feature_disabled') . "</p>";
         }
     }
+
+
+    /**
+     * Ah, legacy code.
+     *
+     * This corrects the original mistakes from 2013 where we used the wrong locale codes. Hopefully we
+     * can get rid of this in a future version, but this should at least give us the belt and suspenders we need
+     * to be sure this change is not too disruptive.
+     *
+     * In this array, we ONLY include the older languages where we weren't using the correct locale codes.
+     *
+     * @author A. Gianotto <snipe@snipe.net>
+     * @since 6.3.0
+     *
+     * @param $language_code
+     * @return string []
+     */
+    public static function mapLegacyLocale($language_code = null)
+    {
+
+        if (strlen($language_code) > 4) {
+            return $language_code;
+        }
+
+        $languages = [
+            'af' => 'af-ZA', // Afrikaans
+            'am' => 'am-ET', // Amharic
+            'ar' => 'ar-SA', // Arabic
+            'bg' => 'bg-BG', // Bulgarian
+            'ca' => 'ca-ES', // Catalan
+            'cs' => 'cs-CZ', // Czech
+            'cy' => 'cy-GB', // Welsh
+            'da' => 'da-DK', // Danish
+            'de-i' => 'de-if', // German informal
+            'de' => 'de-DE', // German
+            'el' => 'el-GR', // Greek
+            'en' => 'en-US', // English
+            'et' => 'et-EE', // Estonian
+            'fa' => 'fa-IR', // Persian
+            'fi' => 'fi-FI', // Finnish
+            'fil' => 'fil-PH', // Filipino
+            'fr' => 'fr-FR', // French
+            'he' => 'he-IL', // Hebrew
+            'hr' => 'hr-HR', // Croatian
+            'hu' => 'hu-HU', // Hungarian
+            'id' => 'id-ID', // Indonesian
+            'is' => 'is-IS', // Icelandic
+            'it' => 'it-IT', // Italian
+            'iu' => 'iu-NU', // Inuktitut
+            'ja' => 'ja-JP', // Japanese
+            'ko' => 'ko-KR', // Korean
+            'lt' => 'lt-LT', // Lithuanian
+            'lv' => 'lv-LV', // Latvian
+            'mi' => 'mi-NZ', // Maori
+            'mk' => 'mk-MK', // Macedonian
+            'mn' => 'mn-MN', // Mongolian
+            'ms' => 'ms-MY', // Malay
+            'nl' => 'nl-NL', // Dutch
+            'no' => 'no-NO', // Norwegian
+            'pl' => 'pl-PL', // Polish
+            'ro' => 'ro-RO', // Romanian
+            'ru' => 'ru-RU', // Russian
+            'sk' => 'sk-SK', // Slovak
+            'sl' => 'sl-SI', // Slovenian
+            'so' => 'so-SO', // Somali
+            'ta' => 'ta-IN', // Tamil
+            'th' => 'th-TH', // Thai
+            'tl' => 'tl-PH', // Tagalog
+            'tr' => 'tr-TR', // Turkish
+            'uk' => 'uk-UA', // Ukrainian
+            'vi' => 'vi-VN', // Vietnamese
+            'zu' => 'zu-ZA', // Zulu
+        ];
+
+        foreach ($languages as $legacy => $new) {
+            if ($language_code == $legacy) {
+                \Log::debug('Current language is '.$legacy.', using '.$new.' instead');
+                return $new;
+            }
+        }
+    }
+
 }