diff --git a/phpBB/includes/functions_admin.php b/phpBB/includes/functions_admin.php
index 67dd3212d3..e1adc3e39e 100644
--- a/phpBB/includes/functions_admin.php
+++ b/phpBB/includes/functions_admin.php
@@ -2832,56 +2832,34 @@ function view_warned_users(&$users, &$user_count, $limit = 0, $offset = 0, $limi
 
 /**
 * Get database size
-* Currently only mysql and mssql are supported
 */
 function get_database_size()
 {
-	global $db, $user, $table_prefix;
+	global $db, $user;
 
 	$database_size = false;
 
-	// This code is heavily influenced by a similar routine in phpMyAdmin 2.2.0
 	switch ($db->get_sql_layer())
 	{
 		case 'mysqli':
-			$sql = 'SELECT VERSION() AS mysql_version';
-			$result = $db->sql_query($sql);
-			$row = $db->sql_fetchrow($result);
-			$db->sql_freeresult($result);
+			$mysql_engine	= ['MyISAM', 'InnoDB', 'Aria'];
 
-			if ($row)
+			$db_name		= $db->get_db_name();
+
+			$sql = 'SHOW TABLE STATUS
+				FROM ' . $db_name;
+			$result = $db->sql_query($sql, 7200);
+
+			while ($row = $db->sql_fetchrow($result))
 			{
-				$version = $row['mysql_version'];
-
-				if (preg_match('#(3\.23|[45]\.|10\.[0-9]\.[0-9]{1,2}-+Maria)#', $version))
+				if (isset($row['Engine']) && in_array($row['Engine'], $mysql_engine))
 				{
-					$db_name = (preg_match('#^(?:3\.23\.(?:[6-9]|[1-9]{2}))|[45]\.|10\.[0-9]\.[0-9]{1,2}-+Maria#', $version)) ? "`{$db->get_db_name()}`" : $db->get_db_name();
-
-					$sql = 'SHOW TABLE STATUS
-						FROM ' . $db_name;
-					$result = $db->sql_query($sql, 7200);
-
-					$database_size = 0;
-					while ($row = $db->sql_fetchrow($result))
-					{
-						if ((isset($row['Type']) && $row['Type'] != 'MRG_MyISAM') || (isset($row['Engine']) && ($row['Engine'] == 'MyISAM' || $row['Engine'] == 'InnoDB' || $row['Engine'] == 'Aria')))
-						{
-							if ($table_prefix != '')
-							{
-								if (strpos($row['Name'], $table_prefix) !== false)
-								{
-									$database_size += $row['Data_length'] + $row['Index_length'];
-								}
-							}
-							else
-							{
-								$database_size += $row['Data_length'] + $row['Index_length'];
-							}
-						}
-					}
-					$db->sql_freeresult($result);
+					$database_size += $row['Data_length'] + $row['Index_length'];
 				}
 			}
+
+			$db->sql_freeresult($result);
+
 		break;
 
 		case 'sqlite3':
diff --git a/tests/functional/acp_main_test.php b/tests/functional/acp_main_test.php
new file mode 100644
index 0000000000..d392102e1a
--- /dev/null
+++ b/tests/functional/acp_main_test.php
@@ -0,0 +1,31 @@
+<?php
+/**
+*
+* This file is part of the phpBB Forum Software package.
+*
+* @copyright (c) phpBB Limited <https://www.phpbb.com>
+* @license GNU General Public License, version 2 (GPL-2.0)
+*
+* For full copyright and license information, please see
+* the docs/CREDITS.txt file.
+*
+*/
+
+/**
+* @group functional
+*/
+class phpbb_functional_acp_main_test extends phpbb_functional_test_case
+{
+	public function test_acp_database_size()
+	{
+		$this->add_lang(['acp/common', 'acp/board']);
+		$this->login();
+		$this->admin_login();
+
+		$crawler = self::request('GET', 'adm/index.php?sid=' . $this->sid);
+		$this->assertContainsLang('WELCOME_PHPBB', $this->get_content());
+		$this->assertContainsLang('ADMIN_INTRO', $this->get_content());
+		$this->assertContainsLang('DATABASE_SIZE', $crawler->filter('tbody > tr')->eq(2)->filter('td[class="tabled"]')->eq(0)->text());
+		$this->assertNotContainsLang('NOT_AVAILABLE', $crawler->filter('tbody > tr')->eq(2)->filter('td[class="tabled"]')->eq(1)->text());
+	}
+}