--- modules/mollom/mollom.module        2008-07-06 21:27:13.000000000 +0100
+++ modules/mollom/mollom_patched.module        2008-09-15 22:36:00.000000000 +0100
@@ -790,6 +790,8 @@ function mollom_protect_form_captcha(&$f
     }
   }
   else {
+    form_set_error('captcha', t('The form data has been altered, the session-id field is required.'));
+
     // Generate a new CAPTCHA:
     $GLOBALS['mollom_captcha'] = mollom('mollom.getImageCaptcha', array('author_ip' => _mollom_ip_address()));
   }