diff --git a/man/udev.xml b/man/udev.xml
index 7b42d2326b..8e58ead0ba 100644
--- a/man/udev.xml
+++ b/man/udev.xml
@@ -465,6 +465,9 @@
Starting daemons or other long-running processes is not appropriate
for udev; the forked processes, detached or not, will be unconditionally
killed after the event handling has finished.
+ Note that running programs that access the network or mount/unmount
+ filesystems is not allowed inside of udev rules, due to the default sandbox
+ that is enforced on systemd-udevd.service.