diff --git a/checkin_notes b/checkin_notes
index f6efc9dd72..6fb15ee69c 100644
--- a/checkin_notes
+++ b/checkin_notes
@@ -6378,3 +6378,9 @@ David  9 Aug 2008
         cs_prefs.C
     html/inc/
         forum.inc
+
+Rytis  9 Aug 2008
+    - web: fix thread being marked as unread after posting to it (fix #506)
+    
+    html/inc/
+        forum.inc
diff --git a/html/inc/forum.inc b/html/inc/forum.inc
index edaf68e0dc..0f2b2551b2 100644
--- a/html/inc/forum.inc
+++ b/html/inc/forum.inc
@@ -271,9 +271,9 @@ function thread_last_visit($user, $thread) {
 
 function thread_is_unread($user, $thread) {
     if (!$user) return false;
-    if ($thread->timestamp < $user->prefs->mark_as_read_timestamp) return false;
+    if ($thread->timestamp <= $user->prefs->mark_as_read_timestamp) return false;
     $log = BoincForumLogging::lookup($user->id, $thread->id);
-    if ($log && ($thread->timestamp < $log->timestamp)) return false;
+    if ($log && ($thread->timestamp <= $log->timestamp)) return false;
     return true;
 }