diff --git a/mod/workshop/locallib.php b/mod/workshop/locallib.php
index 3bafd0cbbbb..e417d532c76 100644
--- a/mod/workshop/locallib.php
+++ b/mod/workshop/locallib.php
@@ -157,6 +157,7 @@ function workshop_copy_assessment($assessment, $submission, $withfeedback = fals
     
     if ($grades = get_records("workshop_grades", "assessmentid", $assessment->id)) {
         foreach ($grades as $grade) {
+            unset($grade->id); // clear id, insert record now seems to believe it!
             if (!$withfeedback) {
                 $grade->feedback = '';
             }