diff --git a/leadboxer.info.yml b/leadboxer.info.yml
index bd251c2..aa7070c 100644
--- a/leadboxer.info.yml
+++ b/leadboxer.info.yml
@@ -2,5 +2,5 @@ name: 'LeadBoxer'
 type: module
 description: 'Adds the LeadBoxer Lead Pixel to your website to capture Leads on your site.'
 package: Statistics
-core: 8.x
+core_version_requirement: ^8 || ^9
 configure: leadboxer.admin_settings_form
diff --git a/leadboxer.module b/leadboxer.module
index ea3eade..4bc3209 100644
--- a/leadboxer.module
+++ b/leadboxer.module
@@ -134,11 +134,11 @@ function _leadboxer_visibility_pages() {
     if (!empty($visibility_request_path_pages)) {
       // Convert path to lowercase. This allows comparison of the same path
       // with different case. Ex: /Page, /page, /PAGE.
-      $pages = Unicode::strtolower($visibility_request_path_pages);
+      $pages = mb_strtolower($visibility_request_path_pages);
       if ($visibility_request_path_mode < 2) {
         // Compare the lowercase path alias (if any) and internal path.
         $path = \Drupal::service('path.current')->getPath();
-        $path_alias = Unicode::strtolower(\Drupal::service('path.alias_manager')->getAliasByPath($path));
+        $path_alias = mb_strtolower(\Drupal::service('path.alias_manager')->getAliasByPath($path));
         $page_match = \Drupal::service('path.matcher')->matchPath($path_alias, $pages) || (($path != $path_alias) && \Drupal::service('path.matcher')->matchPath($path, $pages));
         // When $visibility_request_path_mode has a value of 0, the tracking
         // code is displayed on all pages except those listed in $pages. When
diff --git a/src/Tests/LeadBoxerBasicTest.php b/src/Tests/LeadBoxerBasicTest.php
index 634da95..673adf7 100644
--- a/src/Tests/LeadBoxerBasicTest.php
+++ b/src/Tests/LeadBoxerBasicTest.php
@@ -4,14 +4,14 @@ namespace Drupal\leadboxer\Tests;
 
 use Drupal\Core\Session\AccountInterface;
 use Drupal\Core\Url;
-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;
 
 /**
  * Test basic functionality of LeadBoxer module.
  *
  * @group LeadBoxer
  */
-class LeadBoxerBasicTest extends WebTestBase {
+class LeadBoxerBasicTest extends BrowserTestBase {
 
   /**
    * Modules to enable.
diff --git a/src/Tests/LeadBoxerRolesTest.php b/src/Tests/LeadBoxerRolesTest.php
index 66683ad..3b0d037 100644
--- a/src/Tests/LeadBoxerRolesTest.php
+++ b/src/Tests/LeadBoxerRolesTest.php
@@ -3,14 +3,14 @@
 namespace Drupal\leadboxer\Tests;
 
 use Drupal\Core\Session\AccountInterface;
-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;
 
 /**
  * Test roles functionality of LeadBoxer module.
  *
  * @group LeadBoxer
  */
-class LeadBoxerRolesTest extends WebTestBase {
+class LeadBoxerRolesTest extends BrowserTestBase {
 
   /**
    * Modules to enable.