diff --git a/man7/cgroups.7 b/man7/cgroups.7
index 35f8bd634..7225db320 100644
--- a/man7/cgroups.7
+++ b/man7/cgroups.7
@@ -914,6 +914,7 @@ the delegater might instead add selected controllers to this file.)
 .IR /dlgt_grp/cgroup.threads
 Changing the ownership of this file is necessary if a threaded subtree
 is being delegated (see the description of "thread mode", below).
+This permits the delegatee to write thread IDs to the file.
 .PP
 The delegater should
 .I not