diff --git a/docs/tutorial/notifications.md b/docs/tutorial/notifications.md
index 2ded823f9178..d6323726b59a 100644
--- a/docs/tutorial/notifications.md
+++ b/docs/tutorial/notifications.md
@@ -85,3 +85,5 @@ Notifications are sent using `libnotify` which can show notifications on any
 desktop environment that follows [Desktop Notifications
 Specification][notification-spec], including Cinnamon, Enlightenment, Unity,
 GNOME, KDE.
+
+[notification-spec]: https://developer.gnome.org/notification-spec/