diff --git a/typo3/sysext/rte_ckeditor/Classes/Form/Element/RichTextElement.php b/typo3/sysext/rte_ckeditor/Classes/Form/Element/RichTextElement.php
index a45db40ae6bfbdac99020244234c0003cfa65c63..5750924ab3dcdaf4a35a843cacae6350db7014e7 100644
--- a/typo3/sysext/rte_ckeditor/Classes/Form/Element/RichTextElement.php
+++ b/typo3/sysext/rte_ckeditor/Classes/Form/Element/RichTextElement.php
@@ -376,7 +376,9 @@ class RichTextElement extends AbstractFormElement
             ->getConfiguration();
 
         // Set the UI language of the editor if not hard-coded by the existing configuration
-        if (empty($configuration['language'])) {
+        if (empty($configuration['language']) ||
+            (is_array($configuration['language']) && empty($configuration['language']['ui']))
+        ) {
             $userLang = (string)($this->getBackendUser()->user['lang'] ?: 'en');
             $configuration['language']['ui'] = $userLang === 'default' ? 'en' : $userLang;
         } elseif (!is_array($configuration['language'])) {