diff --git a/grade/edit/tree/category_form.php b/grade/edit/tree/category_form.php
index ac89c55..46878cd 100644
--- a/grade/edit/tree/category_form.php
+++ b/grade/edit/tree/category_form.php
@@ -446,7 +446,7 @@ class edit_category_form extends moodleform {
                         $element =& $mform->createElement('text', 'grade_item_aggregationcoef', get_string($coefstring, 'grades'));
                     }
                     $mform->insertElementBefore($element, 'parentcategory');
-                    $mform->setDefault('grade_item_aggregationcoef', (int) $grade_item->aggregationcoef); // must be cast to int, otherwise "0" counts as true :S
+                    $mform->setDefault('grade_item_aggregationcoef', format_float($grade_item->aggregationcoef, 4)); // must be cast to int, otherwise "0" counts as true :S
                     $mform->setHelpButton('grade_item_aggregationcoef', array($coefstring, get_string($coefstring, 'grades'), 'grade'), true);
                 }
             }