diff --git a/share/man/man4/pf.4 b/share/man/man4/pf.4
index 4055c66fbbc..4f0ff50d3db 100644
--- a/share/man/man4/pf.4
+++ b/share/man/man4/pf.4
@@ -1219,6 +1219,9 @@ and then
 .Pp
 This implementation is derived from
 .Ox 4.5 .
+A number of individual features, improvements, bug fixes and security fixes
+have been ported from later versions of
+.Ox .
 It has been heavily modified to be capable of running in multithreaded
 .Fx
 kernel and scale its performance on multiple CPUs.