diff --git a/phpBB/config/default/container/services_content.yml b/phpBB/config/default/container/services_content.yml
index 6717c20337..8b240067e4 100644
--- a/phpBB/config/default/container/services_content.yml
+++ b/phpBB/config/default/container/services_content.yml
@@ -71,3 +71,4 @@ services:
         class: phpbb\viewonline_helper
         arguments:
             - '@filesystem'
+            - '@dbal.conn'
diff --git a/phpBB/phpbb/viewonline_helper.php b/phpBB/phpbb/viewonline_helper.php
index 89915f2228..9b8c4c50ea 100644
--- a/phpBB/phpbb/viewonline_helper.php
+++ b/phpBB/phpbb/viewonline_helper.php
@@ -21,12 +21,60 @@ class viewonline_helper
 	/** @var \phpbb\filesystem\filesystem_interface */
 	protected $filesystem;
 
+	/** @var \phpbb\db\driver\driver_interface */
+	protected $db;
+
 	/**
 	* @param \phpbb\filesystem\filesystem_interface $filesystem	phpBB's filesystem service
+	* @param \phpbb\db\driver\driver_interface $db
 	*/
-	public function __construct(\phpbb\filesystem\filesystem_interface $filesystem)
+	public function __construct(\phpbb\filesystem\filesystem_interface $filesystem, \phpbb\db\driver\driver_interface $db)
 	{
 		$this->filesystem = $filesystem;
+		$this->db = $db;
+	}
+
+	/**
+	 * Get forum IDs for topics
+	 *
+	 * Retrieve forum IDs and add the data into the session data array
+	 * Array structure matches sql_fethrowset() result array
+	 *
+	 * @param string $session_data_rowset Users' session data array
+	 *
+	 * @return void
+	 */
+	public function get_forum_ids(&$session_data_rowset)
+	{
+		$topic_ids = $match = [];
+		foreach ($session_data_rowset as $number => $row)
+		{
+			if ($row['session_forum_id'] == 0 && preg_match('#t=([0-9]+)#', $row['session_page'], $match))
+			{
+				$topic_ids[$number] = (int) $match[1];
+			}
+		}
+
+		if (count($topic_ids = array_unique($topic_ids)))
+		{
+			$sql_ary = [
+				'SELECT'	=> 't.topic_id, t.forum_id',
+				'FROM'		=> [
+					TOPICS_TABLE => 't',
+				],
+				'WHERE'		=> $this->db->sql_in_set('t.topic_id', $topic_ids),
+				'ORDER_BY'	=> 't.topic_id',
+			];
+			$result = $this->db->sql_query($this->db->sql_build_query('SELECT', $sql_ary));
+			$forum_ids_rowset = $this->db->sql_fetchrowset($result);
+			$this->db->sql_freeresult($result);
+
+			foreach ($forum_ids_rowset as $forum_ids_row)
+			{
+				$session_data_row_number = array_search((int) $forum_ids_row['topic_id'], $topic_ids);
+				$session_data_rowset[$session_data_row_number]['session_forum_id'] = (int) $forum_ids_row['forum_id'];
+			}
+		}
 	}
 
 	/**
diff --git a/phpBB/viewonline.php b/phpBB/viewonline.php
index 1b28750a0b..c9c7e730a5 100644
--- a/phpBB/viewonline.php
+++ b/phpBB/viewonline.php
@@ -180,6 +180,8 @@ $vars = array('sql_ary', 'show_guests', 'guest_counter', 'forum_data');
 extract($phpbb_dispatcher->trigger_event('core.viewonline_modify_sql', compact($vars)));
 
 $result = $db->sql_query($db->sql_build_query('SELECT', $sql_ary));
+$session_data_rowset = $db->sql_fetchrowset($result);
+$db->sql_freeresult($result);
 
 $prev_id = $prev_ip = $user_list = array();
 $logged_visible_online = $logged_hidden_online = $counter = 0;
@@ -190,7 +192,10 @@ $controller_helper = $phpbb_container->get('controller.helper');
 /** @var \phpbb\group\helper $group_helper */
 $group_helper = $phpbb_container->get('group_helper');
 
-while ($row = $db->sql_fetchrow($result))
+// Get forum IDs for session pages which have only 't' parameter
+$viewonline_helper->get_forum_ids($session_data_rowset);
+
+foreach ($session_data_rowset as $row)
 {
 	if ($row['user_id'] != ANONYMOUS && !isset($prev_id[$row['user_id']]))
 	{
@@ -438,7 +443,6 @@ while ($row = $db->sql_fetchrow($result))
 
 	$template->assign_block_vars('user_row', $template_row);
 }
-$db->sql_freeresult($result);
 unset($prev_id, $prev_ip);
 
 $order_legend = ($config['legend_sort_groupname']) ? 'group_name' : 'group_legend';
diff --git a/tests/functional/viewonline_test.php b/tests/functional/viewonline_test.php
new file mode 100644
index 0000000000..a6aed91661
--- /dev/null
+++ b/tests/functional/viewonline_test.php
@@ -0,0 +1,118 @@
+<?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_viewonline_test extends phpbb_functional_test_case
+{
+	
+	protected function get_forum_name_by_topic_id($topic_id)
+	{
+		$db = $this->get_db();
+
+		// Forum info
+		$sql =  'SELECT f.forum_name
+			FROM ' . FORUMS_TABLE . ' f,' . TOPICS_TABLE . ' t
+			WHERE t.forum_id = f.forum_id
+				AND t.topic_id = ' . (int) $topic_id;
+		$result = $db->sql_query($sql);
+		$forum_name = $db->sql_fetchfield('forum_name');
+		$db->sql_freeresult($result, 1800); // cache for 30 minutes
+
+		return $forum_name;
+	}
+
+	protected function get_forum_name_by_forum_id($forum_id)
+	{
+		$db = $this->get_db();
+
+		// Forum info
+		$sql =  'SELECT forum_name
+			FROM ' . FORUMS_TABLE . ' 
+			WHERE forum_id = ' . (int) $topic_id;
+		$result = $db->sql_query($sql);
+		$forum_name = $db->sql_fetchfield('forum_name');
+		$db->sql_freeresult($result, 1800); // cache for 30 minutes
+
+		return $forum_name;
+	}
+
+	public function test_viewonline_reply_mode()
+	{
+		$this->create_user('viewonline-test-user');
+		$this->logout();
+		$this->login('viewonline-test-user');
+		$crawler = self::request('GET', 'posting.php?mode=reply&t=1&sid=' . $this->sid);
+		$this->assertContainsLang('POST_REPLY', $crawler->text());
+
+		// Log in as another user
+		$this->logout();
+		$this->login();
+		$crawler = self::request('GET', 'viewonline.php?sid=' . $this->sid);
+		$this->assertContainsLang('FORUM_LOCATION', $crawler->text());
+
+		// Make sure posting reply page is in the list
+		$this->assertStringContainsString('viewonline-test-user', $crawler->text());
+		$this->assertStringContainsString($this->lang('REPLYING_MESSAGE', $this->get_forum_name_by_topic_id(1)), $crawler->text());
+	}
+
+	public function test_viewonline_posting_mode()
+	{
+		$this->logout();
+		$this->login('viewonline-test-user');
+		$crawler = self::request('GET', 'posting.php?mode=post&f=1&sid=' . $this->sid);
+		$this->assertContainsLang('POST_TOPIC', $crawler->text());
+
+		// Log in as another user
+		$this->logout();
+		$this->login();
+		$crawler = self::request('GET', 'viewonline.php?sid=' . $this->sid);
+
+		// Make sure posting message page is in the list
+		$this->assertStringContainsString('viewonline-test-user', $crawler->text());
+		$this->assertStringContainsString($this->lang('POSTING_MESSAGE', $this->get_forum_name_by_forum_id(2)), $crawler->text());
+	}
+
+	public function test_viewonline_reading_topic()
+	{
+		$this->logout();
+		$this->login('viewonline-test-user');
+		$crawler = self::request('GET', 'viewtopic.php?t=1&sid=' . $this->sid);
+
+		// Log in as another user
+		$this->logout();
+		$this->login();
+		$crawler = self::request('GET', 'viewonline.php?sid=' . $this->sid);
+
+		// Make sure the page is in the list
+		$this->assertStringContainsString('viewonline-test-user', $crawler->text());
+		$this->assertStringContainsString($this->lang('READING_TOPIC', $this->get_forum_name_by_topic_id(1)), $crawler->text());
+	}
+
+	public function test_viewonline_reading_forum()
+	{
+		$this->logout();
+		$this->login('viewonline-test-user');
+		$crawler = self::request('GET', 'viewforum.php?f=2&sid=' . $this->sid);
+
+		// Log in as another user
+		$this->logout();
+		$this->login();
+		$crawler = self::request('GET', 'viewonline.php?sid=' . $this->sid);
+
+		// Make sure the page is in the list
+		$this->assertStringContainsString('viewonline-test-user', $crawler->text());
+		$this->assertStringContainsString($this->lang('READING_FORUM', $this->get_forum_name_by_forum_id(2)), $crawler->text());
+	}
+}