diff --git a/mod/assign/locallib.php b/mod/assign/locallib.php
index 76501587a2d..1cbce58e830 100644
--- a/mod/assign/locallib.php
+++ b/mod/assign/locallib.php
@@ -10094,7 +10094,7 @@ function move_group_override($id, $move, $assignid) {
     global $DB;
 
     // Get the override object.
-    if (!$override = $DB->get_record('assign_overrides', ['id' => $id], 'id, sortorder, groupid')) {
+    if (!$override = $DB->get_record('assign_overrides', ['id' => $id, 'assignid' => $assignid], 'id, sortorder, groupid')) {
         return false;
     }
     // Count the number of group overrides.
@@ -10123,8 +10123,8 @@ function move_group_override($id, $move, $assignid) {
 
         // Delete cache for the 2 records we updated above.
         $cache = cache::make('mod_assign', 'overrides');
-        $cache->delete("{$override->assignid}_g_{$override->groupid}");
-        $cache->delete("{$swapoverride->assignid}_g_{$swapoverride->groupid}");
+        $cache->delete("{$assignid}_g_{$override->groupid}");
+        $cache->delete("{$assignid}_g_{$swapoverride->groupid}");
     }
 
     reorder_group_overrides($assignid);