diff --git a/phpBB/phpbb/session.php b/phpBB/phpbb/session.php
index 4c2471ab92..18fb050a75 100644
--- a/phpBB/phpbb/session.php
+++ b/phpBB/phpbb/session.php
@@ -1663,7 +1663,7 @@ class session
 		}
 
 		// Do not update the session page for ajax requests, so the view online still works as intended
-		$page_changed = $this->update_session_page && (!isset($this->data['session_page']) || $this->data['session_page'] != $this->page['page']) && !$request->is_ajax();
+		$page_changed = $this->update_session_page && (!isset($this->data['session_page']) || $this->data['session_page'] != $this->page['page'] || $this->data['session_forum_id'] != $this->page['forum']) && !$request->is_ajax();
 
 		// Only update session DB a minute or so after last update or if page changes
 		if ($this->time_now - (isset($this->data['session_time']) ? $this->data['session_time'] : 0) > 60 || $page_changed)
diff --git a/phpBB/posting.php b/phpBB/posting.php
index bb43a349f2..79ba5585e9 100644
--- a/phpBB/posting.php
+++ b/phpBB/posting.php
@@ -104,8 +104,17 @@ switch ($mode)
 			trigger_error('NO_POST');
 		}
 
+		// Need to update session forum_id to valid value for proper viewonline information
+		if (!$forum_id)
+		{
+			$user->page['forum'] = (int) $topic_forum['forum_id'];
+			$user->update_session_page = true;
+			$user->update_session_infos();
+		}
+
 		$topic_id = (int) $topic_forum['topic_id'];
 		$forum_id = (int) $topic_forum['forum_id'];
+
 	break;
 }
 
diff --git a/tests/functional/viewonline_test.php b/tests/functional/viewonline_test.php
index 871d43792d..882c48a5e1 100644
--- a/tests/functional/viewonline_test.php
+++ b/tests/functional/viewonline_test.php
@@ -38,7 +38,7 @@ class phpbb_functional_viewonline_test extends phpbb_functional_test_case
 
 		// Forum info
 		$sql =  'SELECT forum_name
-			FROM ' . FORUMS_TABLE . ' 
+			FROM ' . FORUMS_TABLE . '
 			WHERE forum_id = ' . (int) $forum_id;
 		$result = $db->sql_query($sql);
 		$forum_name = $db->sql_fetchfield('forum_name');
@@ -81,6 +81,22 @@ class phpbb_functional_viewonline_test extends phpbb_functional_test_case
 		$this->assertStringContainsString('viewonline-test-user1', $crawler->text());
 		$this->assertStringContainsString($this->lang('POSTING_MESSAGE', $this->get_forum_name_by_forum_id(2)), $crawler->text());
 
+		// Log in as test user
+		self::$client->restart();
+		$this->login('viewonline-test-user1');
+		$test_post_data = $this->create_post(2, 1, 'Viewonline test post #1', 'Viewonline test post message');
+		$crawler = self::request('GET', 'posting.php?mode=edit&p=' . $test_post_data['post_id'] .  '&sid=' . $this->sid);
+		$this->assertContainsLang('EDIT_POST', $crawler->text());
+		// Log in as another user
+		self::$client->restart();
+		$this->login();
+		// PHP goes faster than DBMS, make sure session data got written to the database
+		sleep(1);
+		$crawler = self::request('GET', 'viewonline.php?sid=' . $this->sid);
+		// Make sure posting message page is in the list
+		$this->assertStringContainsString('viewonline-test-user1', $crawler->text());
+		$this->assertStringContainsString($this->lang('POSTING_MESSAGE', $this->get_forum_name_by_forum_id(2)), $crawler->text());
+
 		// Log in as test user
 		self::$client->restart();
 		$this->login('viewonline-test-user1');