diff --git a/adminer/include/adminer.inc.php b/adminer/include/adminer.inc.php
index b21ae673..9efbfe7a 100644
--- a/adminer/include/adminer.inc.php
+++ b/adminer/include/adminer.inc.php
@@ -97,7 +97,7 @@ class Adminer {
 	* @param bool $dark dark CSS: false to disable, true to force, null to base on user preferences
 	* @return bool true to link favicon.ico
 	*/
-	function head(bool $dark = null): bool {
+	function head(?bool $dark = null): bool {
 		// this is matched by compile.php
 		echo "<link rel='stylesheet' href='../externals/jush/jush.css'>\n";
 		echo ($dark !== false ? "<link rel='stylesheet'" . ($dark ? "" : " media='(prefers-color-scheme: dark)'") . " href='../externals/jush/jush-dark.css'>\n" : "");
@@ -304,7 +304,7 @@ class Adminer {
 	* @param Field[] $fields
 	* @param TableStatus $tableStatus
 	*/
-	function tableStructurePrint(array $fields, array $tableStatus = null): void {
+	function tableStructurePrint(array $fields, ?array $tableStatus = null): void {
 		echo "<div class='scrollable'>\n";
 		echo "<table class='nowrap odds'>\n";
 		echo "<thead><tr><th>" . lang('Column') . "<td>" . lang('Type') . (support("comment") ? "<td>" . lang('Comment') : "") . "</thead>\n";
diff --git a/adminer/include/functions.inc.php b/adminer/include/functions.inc.php
index 3c9682cc..1e72ae5a 100644
--- a/adminer/include/functions.inc.php
+++ b/adminer/include/functions.inc.php
@@ -386,7 +386,7 @@ function set_session(string $key, $val) {
 }
 
 /** Get authenticated URL */
-function auth_url(string $vendor, ?string $server, string $username, string $db = null): string {
+function auth_url(string $vendor, ?string $server, string $username, ?string $db = null): string {
 	$uri = remove_from_uri(implode("|", array_keys(SqlDriver::$drivers))
 		. "|username|ext|"
 		. ($db !== null ? "db|" : "")
@@ -412,7 +412,7 @@ function is_ajax(): bool {
 /** Send Location header and exit
 * @param ?string $location null to only set a message
 */
-function redirect(?string $location, string $message = null): void {
+function redirect(?string $location, ?string $message = null): void {
 	if ($message !== null) {
 		restart_session();
 		$_SESSION["messages"][preg_replace('~^[^?]*~', '', ($location !== null ? $location : $_SERVER["REQUEST_URI"]))][] = $message;
diff --git a/adminer/include/html.inc.php b/adminer/include/html.inc.php
index 04469ad7..20b86e86 100644
--- a/adminer/include/html.inc.php
+++ b/adminer/include/html.inc.php
@@ -173,7 +173,7 @@ function hidden_fields_get(): void {
 * @param Field $field
 * @param mixed $value string|array
 */
-function enum_input(string $type, string $attrs, array $field, $value, string $empty = null): string {
+function enum_input(string $type, string $attrs, array $field, $value, ?string $empty = null): string {
 	preg_match_all("~'((?:[^']|'')*)'~", $field["length"], $matches);
 	$return = ($empty !== null ? "<label><input type='$type'$attrs value='$empty'" . ((is_array($value) ? in_array($empty, $value) : $value === $empty) ? " checked" : "") . "><i>" . lang('empty') . "</i></label>" : "");
 	foreach ($matches[1] as $i => $val) {
diff --git a/plugins/edit-calendar.php b/plugins/edit-calendar.php
index f56625f6..314b1bc6 100644
--- a/plugins/edit-calendar.php
+++ b/plugins/edit-calendar.php
@@ -15,7 +15,7 @@ class AdminerEditCalendar {
 	* @param string $prepend text to append before first calendar usage
 	* @param string $langPath path to language file, %s stands for language code
 	*/
-	function __construct(string $prepend = null, string $langPath = "jquery-ui/i18n/jquery.ui.datepicker-%s.js") {
+	function __construct($prepend = null, $langPath = "jquery-ui/i18n/jquery.ui.datepicker-%s.js") {
 		$this->prepend = $prepend;
 		$this->langPath = $langPath;
 	}
diff --git a/plugins/file-upload.php b/plugins/file-upload.php
index c6b071f2..bffcfbcd 100644
--- a/plugins/file-upload.php
+++ b/plugins/file-upload.php
@@ -15,7 +15,7 @@ class AdminerFileUpload {
 	* @param string $displayPath prefix for displaying data, null stands for $uploadPath
 	* @param string $extensions regular expression with allowed file extensions
 	*/
-	function __construct(string $uploadPath = "../static/data/", string $displayPath = null, string $extensions = "[a-zA-Z0-9]+") {
+	function __construct($uploadPath = "../static/data/", $displayPath = null, $extensions = "[a-zA-Z0-9]+") {
 		$this->uploadPath = $uploadPath;
 		$this->displayPath = ($displayPath !== null ? $displayPath : $uploadPath);
 		$this->extensions = $extensions;