diff --git a/phpBB/install/convertors/convert_phpbb20.php b/phpBB/install/convertors/convert_phpbb20.php
index da894d440a..9d59e7a6c9 100644
--- a/phpBB/install/convertors/convert_phpbb20.php
+++ b/phpBB/install/convertors/convert_phpbb20.php
@@ -136,7 +136,7 @@ $config_schema = array(
 		'avatar_max_width'		=> 'avatar_max_width',
 		'avatar_max_height'		=> 'avatar_max_height',
 		'default_dateformat'	=> 'phpbb_set_encoding(default_dateformat)',
-		'board_timezone'		=> 'board_timezone',
+		'board_timezone'		=> 'phpbb_convert_timezone(board_timezone)',
 		'allow_privmsg'			=> 'not(privmsg_disable)',
 		'gzip_compress'			=> 'gzip_compress',
 		'coppa_enable'			=> '!is_empty(coppa_mail)',
@@ -896,7 +896,7 @@ if (!$get_info)
 				array('user_lastmark',			'users.user_lastvisit',				'intval'),
 				array('user_lang',				$config['default_lang'],			''),
 				array('',						'users.user_lang',					''),
-				array('user_timezone',			'users.user_timezone',				'floatval'),
+				array('user_timezone',			'users.user_timezone',				'phpbb_convert_timezone'),
 				array('user_dateformat',		'users.user_dateformat',			array('function1' => 'phpbb_set_encoding', 'function2' => 'fill_dateformat')),
 				array('user_inactive_reason',	'',									'phpbb_inactive_reason'),
 				array('user_inactive_time',		'',									'phpbb_inactive_time'),
diff --git a/phpBB/install/convertors/functions_phpbb20.php b/phpBB/install/convertors/functions_phpbb20.php
index 8a06296b16..4076fe2a78 100644
--- a/phpBB/install/convertors/functions_phpbb20.php
+++ b/phpBB/install/convertors/functions_phpbb20.php
@@ -1926,3 +1926,10 @@ function phpbb_check_username_collisions()
 	$drop_sql = 'DROP TABLE ' . USERCONV_TABLE;
 	$db->sql_query($drop_sql);
 }
+
+function phpbb_convert_timezone($timezone)
+{
+	global $config, $db, $phpbb_root_path, $phpEx, $table_prefix;
+	$timezone_migration = new \phpbb\db\migration\data\v310\timezone($config, $db, new \phpbb\db\tools($db), $phpbb_root_path, $phpEx, $table_prefix);
+	return $timezone_migration->convert_phpbb30_timezone($timezone, 0);
+}