diff --git a/grade/classes/form/add_category.php b/grade/classes/form/add_category.php
index dc754d9e945..8ab7f2e6005 100644
--- a/grade/classes/form/add_category.php
+++ b/grade/classes/form/add_category.php
@@ -431,6 +431,7 @@ class add_category extends dynamic_form {
                     } else {
                         $element =& $mform->createElement('text', 'grade_item_aggregationcoef',
                             get_string($coefstring, 'grades'));
+                        $mform->setType('grade_item_aggregationcoef', PARAM_FLOAT);
                     }
                     $mform->insertElementBefore($element, 'parentcategory');
                     $mform->addHelpButton('grade_item_aggregationcoef', $coefstring, 'grades');
diff --git a/grade/classes/form/add_item.php b/grade/classes/form/add_item.php
index d79186bc093..548f0ac6961 100644
--- a/grade/classes/form/add_item.php
+++ b/grade/classes/form/add_item.php
@@ -303,6 +303,7 @@ class add_item extends dynamic_form {
                     $element =& $mform->createElement('checkbox', 'aggregationcoef', get_string($coefstring, 'grades'));
                 } else {
                     $element =& $mform->createElement('text', 'aggregationcoef', get_string($coefstring, 'grades'));
+                    $mform->setType('aggregationcoef', PARAM_FLOAT);
                 }
                 if ($mform->elementExists('parentcategory')) {
                     $mform->insertElementBefore($element, 'parentcategory');