diff --git a/lib/Froxlor/Api/ApiParameter.php b/lib/Froxlor/Api/ApiParameter.php
index fdefb549..588579e6 100644
--- a/lib/Froxlor/Api/ApiParameter.php
+++ b/lib/Froxlor/Api/ApiParameter.php
@@ -44,7 +44,7 @@ abstract class ApiParameter
 	 *
 	 * @throws Exception
 	 */
-	public function __construct(array $params = null)
+	public function __construct(?array $params = null)
 	{
 		if (!is_null($params)) {
 			$params = $this->trimArray($params);
@@ -91,7 +91,7 @@ abstract class ApiParameter
 	 * @return mixed
 	 * @throws Exception
 	 */
-	protected function getUlParam(string $param = null, string $ul_field = null, bool $optional = false, $default = 0)
+	protected function getUlParam(?string $param = null, ?string $ul_field = null, bool $optional = false, $default = 0)
 	{
 		$param_value = (int)$this->getParam($param, $optional, $default);
 		$ul_field_value = $this->getBoolParam($ul_field, true, 0);
@@ -116,7 +116,7 @@ abstract class ApiParameter
 	 * @return mixed
 	 * @throws Exception
 	 */
-	protected function getParam(string $param = null, bool $optional = false, $default = '')
+	protected function getParam(?string $param = null, bool $optional = false, $default = '')
 	{
 		// does it exist?
 		if (!isset($this->cmd_params[$param])) {
@@ -183,7 +183,7 @@ abstract class ApiParameter
 	 *
 	 * @return string
 	 */
-	protected function getBoolParam(string $param = null, bool $optional = false, $default = false)
+	protected function getBoolParam(?string $param = null, bool $optional = false, $default = false)
 	{
 		$_default = '0';
 		if ($default) {
diff --git a/lib/Froxlor/Database/Database.php b/lib/Froxlor/Database/Database.php
index 14a5fd4b..2c42fb14 100644
--- a/lib/Froxlor/Database/Database.php
+++ b/lib/Froxlor/Database/Database.php
@@ -133,7 +133,7 @@ class Database
 	 *            if set to false, the error will be logged, but we go on
 	 * @throws Exception
 	 */
-	private static function showerror(Exception $error, bool $showerror = true, bool $json_response = false, PDOStatement $stmt = null)
+	private static function showerror(Exception $error, bool $showerror = true, bool $json_response = false, ?PDOStatement $stmt = null)
 	{
 		global $userinfo, $theme, $linker;
 
diff --git a/lib/Froxlor/FroxlorLogger.php b/lib/Froxlor/FroxlorLogger.php
index 5c37bb75..7c29bfea 100644
--- a/lib/Froxlor/FroxlorLogger.php
+++ b/lib/Froxlor/FroxlorLogger.php
@@ -164,7 +164,7 @@ class FroxlorLogger
 	 * @param int $type
 	 * @param ?string $text
 	 */
-	public function logAction($action = FroxlorLogger::USR_ACTION, int $type = LOG_NOTICE, string $text = null)
+	public function logAction($action = FroxlorLogger::USR_ACTION, int $type = LOG_NOTICE, ?string $text = null)
 	{
 		// not logging normal stuff if not set to "paranoid" logging
 		if (!self::$crondebug_flag && Settings::Get('logger.severity') == '1' && $type > LOG_NOTICE) {
diff --git a/lib/Froxlor/PhpHelper.php b/lib/Froxlor/PhpHelper.php
index 7470e90d..5bcc157b 100644
--- a/lib/Froxlor/PhpHelper.php
+++ b/lib/Froxlor/PhpHelper.php
@@ -199,7 +199,7 @@ class PhpHelper
 	 * @param string|null $nameserver set additional resolver nameserver to use (e.g. 1.1.1.1)
 	 * @return bool|array
 	 */
-	public static function gethostbynamel6(string $host, bool $try_a = true, string $nameserver = null)
+	public static function gethostbynamel6(string $host, bool $try_a = true, ?string $nameserver = null)
 	{
 		$ips = [];
 
@@ -442,7 +442,7 @@ class PhpHelper
 	 * @param bool $asReturn
 	 * @return string
 	 */
-	public static function parseArrayToPhpFile(array $array, string $comment = null, bool $asReturn = false): string
+	public static function parseArrayToPhpFile(array $array, ?string $comment = null, bool $asReturn = false): string
 	{
 		$str = sprintf("<?php\n// %s\n\n", $comment ?? 'autogenerated froxlor file');
 
@@ -464,7 +464,7 @@ class PhpHelper
 	 * @param int $depth
 	 * @return string
 	 */
-	public static function parseArrayToString(array $array, string $key = null, int $depth = 1): string
+	public static function parseArrayToString(array $array, ?string $key = null, int $depth = 1): string
 	{
 		$str = '';
 		if (!is_null($key)) {
diff --git a/lib/Froxlor/UI/Pagination.php b/lib/Froxlor/UI/Pagination.php
index c746527c..f5903346 100644
--- a/lib/Froxlor/UI/Pagination.php
+++ b/lib/Froxlor/UI/Pagination.php
@@ -162,7 +162,7 @@ class Pagination
 	 *
 	 * @return Pagination
 	 */
-	public function addSearch(string $searchtext = null, string $field = null, string $operator = null): Pagination
+	public function addSearch(?string $searchtext = null, string $field = null, string $operator = null): Pagination
 	{
 		if (!isset($this->data['sql_search'])) {
 			$this->data['sql_search'] = [];