diff --git a/mod/workshop/mod_form.php b/mod/workshop/mod_form.php
index 8489fe7105f..a407c2a0c34 100644
--- a/mod/workshop/mod_form.php
+++ b/mod/workshop/mod_form.php
@@ -328,7 +328,7 @@ class mod_workshop_mod_form extends moodleform_mod {
      * @return array eventual errors indexed by the field name
      */
     public function validation($data, $files) {
-        $errors = array();
+        $errors = parent::validation($data, $files);
 
         // check the phases borders are valid
         if ($data['submissionstart'] > 0 and $data['submissionend'] > 0 and $data['submissionstart'] >= $data['submissionend']) {