diff --git a/question/type/calculated/questiontype.php b/question/type/calculated/questiontype.php
index f8bcd18d9ce..d86d27f9c0c 100644
--- a/question/type/calculated/questiontype.php
+++ b/question/type/calculated/questiontype.php
@@ -607,8 +607,8 @@ class question_calculated_qtype extends question_dataset_dependent_questiontype
                                                 ? 'decimals'
                                                 : 'significantfigures'), 'quiz', $i);
             }
-            return '<input type="submit" onclick="'
-                    . "getElementById('addform').regenerateddefid.value='$defid'; return true;"
+            return '<input type="submit" onClick="'
+                    . "document.addform.regenerateddefid.value='$defid'; return true;"
                     .'" value="'. get_string('generatevalue', 'quiz') . '"/><br/>'
                     . '<input type="text" size="3" name="calcmin[]" '
                     . " value=\"$regs[2]\"/> &amp; <input name=\"calcmax[]\" "