diff --git a/lib/formslib.php b/lib/formslib.php
index b12392b..b111be0 100644
--- a/lib/formslib.php
+++ b/lib/formslib.php
@@ -1024,7 +1024,7 @@ class MoodleQuickForm extends HTML_QuickForm_DHTMLRulesTableless {
     {
         parent::addRule($element, $message, $type, $format, $validation, $reset, $force);
         if ($validation == 'client') {
-            $this->updateAttributes(array('onsubmit' => 'try { var myValidator = validate_' . $this->_formName . '; } catch(e) { return true; } return myValidator(this);'));
+            $this->updateAttributes(array('onsubmit' => 'try { var myValidator = validate_' . $this->_formName.'_'.$this->_attributes['id'].'; } catch(e) { return true; } return myValidator(this);'));
         }
 
     } // end func addRule
@@ -1236,7 +1236,7 @@ function validate_' . $this->_formName . '_' . $elementName . '(element) {
         }
 //  do not rely on frm function parameter, because htmlarea breaks it when overloading the onsubmit method
         $js .= '
-function validate_' . $this->_formName . '(frm) {
+function validate_' . $this->_formName.'_'.$this->_attributes['id'].'(frm) {
   if (skipClientValidation) {
      return true;
   }