diff --git a/adminer/drivers/mssql.inc.php b/adminer/drivers/mssql.inc.php
index c16a0c13..8c5d896b 100644
--- a/adminer/drivers/mssql.inc.php
+++ b/adminer/drivers/mssql.inc.php
@@ -53,7 +53,7 @@ if (isset($_GET["mssql"])) {
 				return ($unicode ? "N" : "") . "'" . str_replace("'", "''", $string) . "'";
 			}
 
-			function select_db(string $database): bool {
+			function select_db(string $database) {
 				return $this->query(use_sql($database));
 			}
 
@@ -159,7 +159,7 @@ if (isset($_GET["mssql"])) {
 
 	} else {
 		abstract class MssqlDb extends PdoDb {
-			function select_db(string $database): bool {
+			function select_db(string $database) {
 				// database selection is separated from the connection so dbname in DSN can't be used
 				return $this->query(use_sql($database));
 			}
diff --git a/adminer/drivers/mysql.inc.php b/adminer/drivers/mysql.inc.php
index 2c74db95..b619d791 100644
--- a/adminer/drivers/mysql.inc.php
+++ b/adminer/drivers/mysql.inc.php
@@ -91,7 +91,7 @@ if (!defined('Adminer\DRIVER')) {
 				return "'" . mysql_real_escape_string($string, $this->link) . "'";
 			}
 
-			function select_db(string $database): bool {
+			function select_db(string $database) {
 				return mysql_select_db($database, $this->link);
 			}
 
@@ -186,7 +186,7 @@ if (!defined('Adminer\DRIVER')) {
 				return $this->query("SET NAMES $charset"); // charset in DSN is ignored before PHP 5.3.6
 			}
 
-			function select_db(string $database): bool {
+			function select_db(string $database) {
 				// database selection is separated from the connection so dbname in DSN can't be used
 				return $this->query("USE " . idf_escape($database));
 			}
diff --git a/adminer/drivers/oracle.inc.php b/adminer/drivers/oracle.inc.php
index 7ec8d4ae..0bbd9f4d 100644
--- a/adminer/drivers/oracle.inc.php
+++ b/adminer/drivers/oracle.inc.php
@@ -33,7 +33,7 @@ if (isset($_GET["oracle"])) {
 				return "'" . str_replace("'", "''", $string) . "'";
 			}
 
-			function select_db(string $database): bool {
+			function select_db(string $database) {
 				$this->_current_db = $database;
 				return true;
 			}
@@ -109,7 +109,7 @@ if (isset($_GET["oracle"])) {
 				return $this->dsn("oci:dbname=//$server;charset=AL32UTF8", $username, $password);
 			}
 
-			function select_db(string $database): bool {
+			function select_db(string $database) {
 				$this->_current_db = $database;
 				return true;
 			}
diff --git a/adminer/drivers/pgsql.inc.php b/adminer/drivers/pgsql.inc.php
index 5c9b0f8b..478519ae 100644
--- a/adminer/drivers/pgsql.inc.php
+++ b/adminer/drivers/pgsql.inc.php
@@ -51,7 +51,7 @@ if (isset($_GET["pgsql"])) {
 				return ($field["type"] == "bytea" && $val !== null ? pg_unescape_bytea($val) : $val);
 			}
 
-			function select_db(string $database): bool {
+			function select_db(string $database) {
 				if ($database == adminer()->database()) {
 					return $this->database;
 				}
@@ -138,7 +138,7 @@ if (isset($_GET["pgsql"])) {
 				return $this->dsn($dsn, $username, $password);
 			}
 
-			function select_db(string $database): bool {
+			function select_db(string $database) {
 				return (adminer()->database() == $database);
 			}
 
diff --git a/adminer/include/db.inc.php b/adminer/include/db.inc.php
index 464fe3a7..93800e4f 100644
--- a/adminer/include/db.inc.php
+++ b/adminer/include/db.inc.php
@@ -25,8 +25,10 @@ abstract class SqlDb {
 	*/
 	abstract function quote(string $string): string;
 
-	/** Select database */
-	abstract function select_db(string $database): bool;
+	/** Select database
+	* @return bool boolish
+	*/
+	abstract function select_db(string $database);
 
 	/** Send query
 	* @return Result|bool
diff --git a/plugins/drivers/clickhouse.php b/plugins/drivers/clickhouse.php
index eae90dd6..78c4782c 100644
--- a/plugins/drivers/clickhouse.php
+++ b/plugins/drivers/clickhouse.php
@@ -63,7 +63,7 @@ if (isset($_GET["clickhouse"])) {
 				return ($return ? '' : $this->error);
 			}
 
-			function select_db(string $database): bool {
+			function select_db(string $database) {
 				$this->_db = $database;
 				return true;
 			}
diff --git a/plugins/drivers/elastic.php b/plugins/drivers/elastic.php
index b22af2cd..7f2c5513 100644
--- a/plugins/drivers/elastic.php
+++ b/plugins/drivers/elastic.php
@@ -71,7 +71,7 @@ if (isset($_GET["elastic"])) {
 				return ($return ? '' : $this->error);
 			}
 
-			function select_db(string $database): bool {
+			function select_db(string $database) {
 				return true;
 			}
 
diff --git a/plugins/drivers/firebird.php b/plugins/drivers/firebird.php
index d81bbd94..119fb10e 100644
--- a/plugins/drivers/firebird.php
+++ b/plugins/drivers/firebird.php
@@ -29,7 +29,7 @@ if (isset($_GET["firebird"])) {
 				return "'" . str_replace("'", "''", $string) . "'";
 			}
 
-			function select_db(string $database): bool {
+			function select_db(string $database) {
 				return ($database == "domain");
 			}
 
diff --git a/plugins/drivers/imap.php b/plugins/drivers/imap.php
index 29583057..37246f32 100644
--- a/plugins/drivers/imap.php
+++ b/plugins/drivers/imap.php
@@ -30,7 +30,7 @@ if (isset($_GET["imap"])) {
 				return ($this->imap ? '' : imap_last_error());
 			}
 
-			function select_db(string $database): bool {
+			function select_db(string $database) {
 				return ($database == "mail");
 			}
 
diff --git a/plugins/drivers/mongo.php b/plugins/drivers/mongo.php
index ae50ac81..174993e1 100644
--- a/plugins/drivers/mongo.php
+++ b/plugins/drivers/mongo.php
@@ -58,7 +58,7 @@ if (isset($_GET["mongo"])) {
 				return false;
 			}
 
-			function select_db(string $database): bool {
+			function select_db(string $database) {
 				$this->_db_name = $database;
 				return true;
 			}
diff --git a/plugins/drivers/simpledb.php b/plugins/drivers/simpledb.php
index 52f558be..ff46ff19 100644
--- a/plugins/drivers/simpledb.php
+++ b/plugins/drivers/simpledb.php
@@ -14,7 +14,7 @@ if (isset($_GET["simpledb"])) {
 				return '';
 			}
 
-			function select_db(string $database): bool {
+			function select_db(string $database) {
 				return ($database == "domain");
 			}