diff --git a/lib/classes/event/notification_sent.php b/lib/classes/event/notification_sent.php
index 1c2080c3c5b..f00fb51227b 100644
--- a/lib/classes/event/notification_sent.php
+++ b/lib/classes/event/notification_sent.php
@@ -58,6 +58,11 @@ class notification_sent extends base {
             $userfromid = 0;
         }
 
+        // If the courseid is null, then set it to the site id.
+        if (is_null($courseid)) {
+            $courseid = SITEID;
+        }
+
         $event = self::create(
             [
                 'objectid' => $notificationid,
diff --git a/message/tests/events_test.php b/message/tests/events_test.php
index 0f31ae0e0d1..9c9c4158edb 100644
--- a/message/tests/events_test.php
+++ b/message/tests/events_test.php
@@ -484,6 +484,23 @@ class core_message_events_testcase extends core_message_messagelib_testcase {
         $this->assertEquals($url, $event->get_url());
     }
 
+    /**
+     * Test the notification sent event when null passed as course.
+     */
+    public function test_notification_sent_with_null_course() {
+        $event = \core\event\notification_sent::create_from_ids(1, 1, 1, null);
+
+        // Trigger and capture the event.
+        $sink = $this->redirectEvents();
+        $event->trigger();
+        $events = $sink->get_events();
+        $event = reset($events);
+
+        // Check that the event data is valid.
+        $this->assertInstanceOf('\core\event\notification_sent', $event);
+        $this->assertEquals(SITEID, $event->other['courseid']);
+    }
+
     /**
      * Test the notification viewed event.
      */