diff --git a/man/systemd.timer.xml b/man/systemd.timer.xml
index ac00d2aec26..9cfb453399c 100644
--- a/man/systemd.timer.xml
+++ b/man/systemd.timer.xml
@@ -124,7 +124,7 @@
OnBootSec=
- Defines a timer relative to when the machine was booted up.
+ Defines a timer relative to when the machine was booted up. In containers, for the system manager instance, this is mapped to OnStartupSec=, making both equivalent.
OnStartupSec=