diff --git a/classes/adminbasecontroller.php b/classes/adminbasecontroller.php
index 647c9e45..03ee9ab6 100644
--- a/classes/adminbasecontroller.php
+++ b/classes/adminbasecontroller.php
@@ -631,7 +631,7 @@ class AdminBaseController
             // now the first 4 chars of base contain the lang code.
             // if redirect path already contains the lang code, and is != than the base lang code, then use redirect path as-is
             if (Utils::pathPrefixedByLangCode($base) && Utils::pathPrefixedByLangCode($this->redirect)
-                && 0 !== strpos($this->redirect, substr($base, 0, 4))
+                && !Utils::startsWith($this->redirect, $base)
             ) {
                 $redirect = $this->redirect;
             } else {
diff --git a/classes/admincontroller.php b/classes/admincontroller.php
index fde70548..a55bdc61 100644
--- a/classes/admincontroller.php
+++ b/classes/admincontroller.php
@@ -2375,18 +2375,19 @@ class AdminController extends AdminBaseController
      */
     public function determineFilenameIncludingLanguage($current_filename, $language)
     {
-        $filename = substr($current_filename, 0, -strlen('.md'));
+        $ext = '.md';
+        $filename = substr($current_filename, 0, -strlen($ext));
+        $languages_enabled = $this->grav['config']->get('system.languages.supported', []);
 
-        if (substr($filename, -3, 1) === '.') {
-            $filename = str_replace(substr($filename, -2), $language, $filename);
-        } elseif (substr($filename, -6, 1) === '.') {
-            $filename = str_replace(substr($filename, -5), $language, $filename);
-        } else {
-            $filename .= '.' . $language;
+        $parts = explode('.', trim($filename, '.'));
+        $lang = array_pop($parts);
+
+        if ($lang === $language) {
+            return $filename . $ext;
+        } elseif (in_array($lang, $languages_enabled)) {
+            $filename = implode('.', $parts);
         }
 
-        return $filename . '.md';
+        return $filename . '.' . $language . $ext;
     }
-
-
 }