diff --git a/course/editsection_form.php b/course/editsection_form.php
index 870f76c75b2..edd156b91d4 100644
--- a/course/editsection_form.php
+++ b/course/editsection_form.php
@@ -180,10 +180,41 @@ class editsection_form extends moodleform {
         // Conditions: Don't let them set dates which make no sense
         if (array_key_exists('availablefrom', $data) &&
                 $data['availablefrom'] && $data['availableuntil'] &&
-                $data['availablefrom'] > $data['availableuntil']) {
+                $data['availablefrom'] >= $data['availableuntil']) {
             $errors['availablefrom'] = get_string('badavailabledates', 'condition');
         }
 
+        // Conditions: Verify that the grade conditions are numbers, and make sense.
+        if (array_key_exists('conditiongradegroup', $data)) {
+            foreach ($data['conditiongradegroup'] as $i => $gradedata) {
+                if ($gradedata['conditiongrademin'] !== '' &&
+                        !is_numeric(unformat_float($gradedata['conditiongrademin']))) {
+                    $errors["conditiongradegroup[{$i}]"] = get_string('gradesmustbenumeric', 'condition');
+                    continue;
+                }
+                if ($gradedata['conditiongrademax'] !== '' &&
+                        !is_numeric(unformat_float($gradedata['conditiongrademax']))) {
+                    $errors["conditiongradegroup[{$i}]"] = get_string('gradesmustbenumeric', 'condition');
+                    continue;
+                }
+                if ($gradedata['conditiongrademin'] !== '' && $gradedata['conditiongrademax'] !== '' &&
+                        unformat_float($gradedata['conditiongrademax']) <= unformat_float($gradedata['conditiongrademin'])) {
+                    $errors["conditiongradegroup[{$i}]"] = get_string('badgradelimits', 'condition');
+                    continue;
+                }
+                if ($gradedata['conditiongrademin'] === '' && $gradedata['conditiongrademax'] === '' &&
+                        $gradedata['conditiongradeitemid']) {
+                    $errors["conditiongradegroup[{$i}]"] = get_string('gradeitembutnolimits', 'condition');
+                    continue;
+                }
+                if (($gradedata['conditiongrademin'] !== '' || $gradedata['conditiongrademax'] !== '') &&
+                        !$gradedata['conditiongradeitemid']) {
+                    $errors["conditiongradegroup[{$i}]"] = get_string('gradelimitsbutnoitem', 'condition');
+                    continue;
+                }
+            }
+        }
+
         return $errors;
     }
 }
diff --git a/course/moodleform_mod.php b/course/moodleform_mod.php
index 292387b9dbd..a62cb976944 100644
--- a/course/moodleform_mod.php
+++ b/course/moodleform_mod.php
@@ -332,7 +332,7 @@ abstract class moodleform_mod extends moodleform {
                     continue;
                 }
                 if ($gradedata['conditiongrademin'] !== '' && $gradedata['conditiongrademax'] !== '' &&
-                        unformat_float($gradedata['conditiongrademax']) < unformat_float($gradedata['conditiongrademin'])) {
+                        unformat_float($gradedata['conditiongrademax']) <= unformat_float($gradedata['conditiongrademin'])) {
                     $errors["conditiongradegroup[{$i}]"] = get_string('badgradelimits', 'condition');
                     continue;
                 }