diff --git a/edit_form.php b/edit_form.php
index 30b5c75..968708b 100644
--- a/edit_form.php
+++ b/edit_form.php
@@ -102,13 +102,8 @@ public function definition () {
         $mform->setDefault('secret', md5(uniqid(rand(), 1)));
         $mform->addRule('secret', get_string('required'), 'required');
 
-        if (class_exists('textlib')) {
-            $textlib = new textlib();
-        } else {
-            $textlib = textlib_get_instance();
-        }
 
-        $choices = $textlib->get_encodings();
+        $choices = core_text::get_encodings();
         $mform->addElement('select', 'encoding', get_string('remoteencoding', 'local_ltiprovider'), $choices);
         $mform->setDefault('encoding', 'UTF-8');
 
@@ -220,4 +215,4 @@ public function validation($data, $files) {
         return $errors;
     }
 
-}
\ No newline at end of file
+}
diff --git a/tool.php b/tool.php
index 7804b3d..1e0e0f9 100644
--- a/tool.php
+++ b/tool.php
@@ -227,17 +227,11 @@
 
     // Transform to utf8 all the post and get data
 
-    if (class_exists('textlib')) {
-        $textlib = new textlib();
-    } else {
-        $textlib = textlib_get_instance();
-    }
-
     foreach ($_POST as $key => $value) {
-        $_POST[$key] = $textlib->convert($value, $tool->encoding);
+        $_POST[$key] = core_text::convert($value, $tool->encoding);
     }
     foreach ($_GET as $key => $value) {
-        $_GET[$key] = $textlib->convert($value, $tool->encoding);
+        $_GET[$key] = core_text::convert($value, $tool->encoding);
     }
 
     // We need an username without extended chars