diff --git a/Smarty/Smarty.class.php b/Smarty/Smarty.class.php
index b298c3276..aa2c3fe59 100644
--- a/Smarty/Smarty.class.php
+++ b/Smarty/Smarty.class.php
@@ -1107,8 +1107,8 @@ public function templateExists($resource_name) {
    *
    * @return \Smarty current Smarty instance for chaining
    */
-  public function setTemplateDir($template_dir, $isConfig = false) {
-    $this->addTemplateDir($template_dir, null, $isConfig);
+  public function setTemplateDir($template_dir) {
+    $this->template_dir = (array) $template_dir;
     return $this;
   }
 
diff --git a/smarty5/Smarty.php b/smarty5/Smarty.php
index 9da8a4ede..a35958563 100644
--- a/smarty5/Smarty.php
+++ b/smarty5/Smarty.php
@@ -1,5 +1,8 @@
 <?php
 
+use Civi\Smarty\Extension;
+use Smarty\Extension\DefaultExtension;
+
 require_once __DIR__ . DIRECTORY_SEPARATOR . 'vendor' . DIRECTORY_SEPARATOR . 'autoload.php';
 class Smarty {
 
@@ -7,11 +10,12 @@ class Smarty {
 
   public function __construct() {
     $this->smarty = new Smarty\Smarty();
+    $this->smarty->addExtension(new Extension());
     global $civicrm_root;
     $pluginsDirectory = $civicrm_root . DIRECTORY_SEPARATOR . 'CRM' . DIRECTORY_SEPARATOR . 'Core' . DIRECTORY_SEPARATOR . 'Smarty'  . DIRECTORY_SEPARATOR . 'plugins';
     $files = scandir($pluginsDirectory);
     foreach ($files as $file) {
-      if (str_starts_with($file, '.')) {
+      if (str_starts_with($file, '.') || str_starts_with($file, 'modifier')) {
         continue;
       }
       if (CRM_Utils_File::isIncludable($pluginsDirectory .DIRECTORY_SEPARATOR . $file)) {
@@ -53,4 +57,8 @@ public function loadFilter($type, $name) {
     }
   }
 
+  public function getVersion(): ?int {
+    return 5;
+  }
+
 }