diff --git a/lib/statslib.php b/lib/statslib.php
index e57e89a07fc..a65b7714373 100644
--- a/lib/statslib.php
+++ b/lib/statslib.php
@@ -1333,7 +1333,7 @@ function stats_get_report_options($courseid,$mode) {
     case STATS_MODE_GENERAL:
         $reportoptions[STATS_REPORT_ACTIVITY] = get_string('statsreport'.STATS_REPORT_ACTIVITY);
         if ($courseid != SITEID && $context = get_context_instance(CONTEXT_COURSE, $courseid)) {
-            $sql = 'SELECT r.id, r.name FROM {role} r JOIN {stats_daily} s ON s.roleid = r.id WHERE s.courseid = :courseid GROUP BY s.roleid';
+            $sql = 'SELECT r.id, r.name FROM {role} r JOIN {stats_daily} s ON s.roleid = r.id WHERE s.courseid = :courseid GROUP BY r.id, r.name';
             if ($roles = $DB->get_records_sql($sql, array('courseid' => $courseid))) {
                 foreach ($roles as $role) {
                     $reportoptions[STATS_REPORT_ACTIVITYBYROLE.$role->id] = get_string('statsreport'.STATS_REPORT_ACTIVITYBYROLE). ' '.$role->name;