diff --git a/grade/edit/tree/category_form.php b/grade/edit/tree/category_form.php
index 98a18a45d09..ef6ada4b10b 100644
--- a/grade/edit/tree/category_form.php
+++ b/grade/edit/tree/category_form.php
@@ -211,6 +211,8 @@ class edit_category_form extends moodleform {
         }
         $mform->addElement('select', 'grade_item_display', get_string('gradedisplaytype', 'grades'), $options);
         $mform->addHelpButton('grade_item_display', 'gradedisplaytype', 'grades');
+        $mform->disabledIf('grade_item_display', 'grade_item_gradetype', 'in',
+            array(GRADE_TYPE_TEXT, GRADE_TYPE_NONE));
 
         $default_gradedecimals = grade_get_setting($COURSE->id, 'decimalpoints', $CFG->grade_decimalpoints);
         $options = array(-1=>get_string('defaultprev', 'grades', $default_gradedecimals), 0=>0, 1=>1, 2=>2, 3=>3, 4=>4, 5=>5);
@@ -218,6 +220,8 @@ class edit_category_form extends moodleform {
         $mform->addHelpButton('grade_item_decimals', 'decimalpoints', 'grades');
         $mform->setDefault('grade_item_decimals', -1);
         $mform->disabledIf('grade_item_decimals', 'grade_item_display', 'eq', GRADE_DISPLAY_TYPE_LETTER);
+        $mform->disabledIf('grade_item_decimals', 'grade_item_gradetype', 'in',
+            array(GRADE_TYPE_TEXT, GRADE_TYPE_NONE));
 
         if ($default_gradedisplaytype == GRADE_DISPLAY_TYPE_LETTER) {
             $mform->disabledIf('grade_item_decimals', 'grade_item_display', "eq", GRADE_DISPLAY_TYPE_DEFAULT);
diff --git a/grade/edit/tree/item_form.php b/grade/edit/tree/item_form.php
index 5dfb8e95136..f762cc7e9c8 100644
--- a/grade/edit/tree/item_form.php
+++ b/grade/edit/tree/item_form.php
@@ -166,6 +166,7 @@ class edit_item_form extends moodleform {
         }
         $mform->addElement('select', 'display', get_string('gradedisplaytype', 'grades'), $options);
         $mform->addHelpButton('display', 'gradedisplaytype', 'grades');
+        $mform->disabledIf('display', 'gradetype', 'eq', GRADE_TYPE_TEXT);
 
         $default_gradedecimals = grade_get_setting($COURSE->id, 'decimalpoints', $CFG->grade_decimalpoints);
         $options = array(-1=>get_string('defaultprev', 'grades', $default_gradedecimals), 0=>0, 1=>1, 2=>2, 3=>3, 4=>4, 5=>5);
@@ -176,6 +177,7 @@ class edit_item_form extends moodleform {
         if ($default_gradedisplaytype == GRADE_DISPLAY_TYPE_LETTER) {
             $mform->disabledIf('decimals', 'display', "eq", GRADE_DISPLAY_TYPE_DEFAULT);
         }
+        $mform->disabledIf('decimals', 'gradetype', 'eq', GRADE_TYPE_TEXT);
 
         /// hiding
         if ($item->cancontrolvisibility) {