diff --git a/conf/config.inc.php b/conf/config.inc.php
index 322d04e..4f9b705 100644
--- a/conf/config.inc.php
+++ b/conf/config.inc.php
@@ -218,7 +218,7 @@
 
 # Smarty
 if (!defined("SMARTY")) {
-    define("SMARTY", "/usr/share/php/smarty3/Smarty.class.php");
+    define("SMARTY", "/usr/share/php/smarty4/Smarty.class.php");
 }
 
 # Allow to override current settings with an extra configuration file, whose reference is passed in HTTP_HEADER $header_name_extra_config
diff --git a/docs/general-parameters.rst b/docs/general-parameters.rst
index 9a52454..d411795 100644
--- a/docs/general-parameters.rst
+++ b/docs/general-parameters.rst
@@ -172,7 +172,7 @@ You need to define where Smarty is installed:
 
 .. code-block:: php
 
-    define("SMARTY", "/usr/share/php/smarty3/Smarty.class.php");
+    define("SMARTY", "/usr/share/php/smarty4/Smarty.class.php");
 
 Notify administrator by mail
 ----------------------------
diff --git a/docs/installation.rst b/docs/installation.rst
index 23caadc..0bf2b2d 100644
--- a/docs/installation.rst
+++ b/docs/installation.rst
@@ -21,7 +21,7 @@ You need to install these prerequisites:
 * Apache or another web server
 * php
 * php-ldap
-* Smarty (version 3)
+* Smarty (version 4)
 
 Debian / Ubuntu
 ---------------
@@ -54,14 +54,14 @@ You are now ready to install:
 
 .. prompt:: bash #
 
-    apt install service-desk smarty3
+    apt install service-desk smarty4
 
 CentOS / RedHat
 ---------------
 
-.. warning:: You may need to install first the package `php-Smarty`_ which is not in official repositories.
+.. warning:: You may need to install first the package `smarty4` which is not in official repositories.
 
-.. _php-Smarty: https://pkgs.org/download/php-Smarty
+.. _smarty4: https://pkgs.org/download/smarty4
 
 Configure the yum repository:
 
diff --git a/htdocs/display.php b/htdocs/display.php
index fd53aad..7e9ba15 100644
--- a/htdocs/display.php
+++ b/htdocs/display.php
@@ -126,7 +126,7 @@
             }
 
             # Lock
-            $pwdLockout = strtolower($ppolicy_entry[0]['pwdlockout'][0]) == "true" ? true : false;
+            $pwdLockout = strtolower(isset($ppolicy_entry[0]['pwdlockout'][0])) == "true" ? true : false;
             $pwdLockoutDuration = $ppolicy_entry[0]['pwdlockoutduration'][0];
             $pwdAccountLockedTime = $entry[0]['pwdaccountlockedtime'][0];
 
diff --git a/htdocs/index.php b/htdocs/index.php
index 66d8985..b5aed89 100644
--- a/htdocs/index.php
+++ b/htdocs/index.php
@@ -82,6 +82,9 @@
 $smarty->setCacheDir($cache_dir);
 $smarty->debugging = $smarty_debug;
 
+# Muting warnings due to PHP 8+
+$smarty->muteUndefinedOrNullWarnings();
+
 error_reporting(0);
 if ($debug) {
     error_reporting(E_ALL);