diff --git a/gnu/usr.bin/groff/tmac/mdoc.local b/gnu/usr.bin/groff/tmac/mdoc.local
index 6fef3433a72d..56cc3ce8e21d 100644
--- a/gnu/usr.bin/groff/tmac/mdoc.local
+++ b/gnu/usr.bin/groff/tmac/mdoc.local
@@ -66,6 +66,7 @@
 .ds doc-operating-system-FreeBSD-4.10   4.10
 .ds doc-operating-system-FreeBSD-5.1    5.1
 .ds doc-operating-system-FreeBSD-5.2    5.2
+.ds doc-operating-system-FreeBSD-5.2.1  5.2.1
 .ds doc-operating-system-FreeBSD-5.3    5.3
 .
 .ec