diff --git a/man2/prctl.2 b/man2/prctl.2
index abed93885..57135d646 100644
--- a/man2/prctl.2
+++ b/man2/prctl.2
@@ -423,7 +423,9 @@ call will cause a
 .B SIGKILL
 signal to be sent to the process.
 If the caller is in filter mode, and this system call is allowed by the
-seccomp filters, it returns 2.
+seccomp filters, it returns 2; otherwise, the process is killed with a
+.BR SIGKILL
+signal.
 This operation is available only
 if the kernel is configured with
 .B CONFIG_SECCOMP