diff --git a/mod/forum/post.php b/mod/forum/post.php
index 8c5c2b9ba99..b8c86cb0593 100644
--- a/mod/forum/post.php
+++ b/mod/forum/post.php
@@ -696,6 +696,9 @@ if ($mformpost->is_cancelled()) {
     // WARNING: the $fromform->message array has been overwritten, do not use it anymore!
     $fromform->messagetrust  = trusttext_trusted($modcontext);
 
+    // Clean message text.
+    $fromform = trusttext_pre_edit($fromform, 'message', $modcontext);
+
     if ($fromform->edit) {           // Updating a post.
         unset($fromform->groupid);
         $fromform->id = $fromform->edit;