Actually switch languages

app/controller/controller.php

@@ -42,7 +42,7 @@ class Controller
 
         foreach (explode(',', LANGUAGES) as $language) {
             foreach ($accept_languages as $accept_language) {
-                if (strpos($language, $accept_language)>=0) {
+                if (substr($language, 0, strlen($accept_language))===$accept_language) {
                     $lang = $language;
                     $lang_short = explode($language, '-')[0];
                 }