diff --git a/man/systemd.service.xml b/man/systemd.service.xml
index c6ed75d158..20a71afe59 100644
--- a/man/systemd.service.xml
+++ b/man/systemd.service.xml
@@ -517,7 +517,12 @@
should be set to open access to the notification socket
provided by systemd. If NotifyAccess= is
not set, it will be implicitly set to .
- Defaults to 0, which disables this feature.
+ Defaults to 0, which disables this feature. The service can
+ check whether the service manager expects watchdog keep-alive
+ notifications. See
+ sd_watchdog_enabled3
+ for details.
+