diff --git a/usr.bin/locale/locale.c b/usr.bin/locale/locale.c
index da4a560b2d2b..cad3afe71bdb 100644
--- a/usr.bin/locale/locale.c
+++ b/usr.bin/locale/locale.c
@@ -190,18 +190,18 @@ struct _kwinfo {
 	{ "abmon_10",		1, LC_TIME,	ABMON_10, "" },
 	{ "abmon_11",		1, LC_TIME,	ABMON_11, "" },
 	{ "abmon_12",		1, LC_TIME,	ABMON_12, "" },
-	{ "altmon_1",		1, LC_TIME,	ALTMON_1, "" },
-	{ "altmon_2",		1, LC_TIME,	ALTMON_2, "" },
-	{ "altmon_3",		1, LC_TIME,	ALTMON_3, "" },
-	{ "altmon_4",		1, LC_TIME,	ALTMON_4, "" },
-	{ "altmon_5",		1, LC_TIME,	ALTMON_5, "" },
-	{ "altmon_6",		1, LC_TIME,	ALTMON_6, "" },
-	{ "altmon_7",		1, LC_TIME,	ALTMON_7, "" },
-	{ "altmon_8",		1, LC_TIME,	ALTMON_8, "" },
-	{ "altmon_9",		1, LC_TIME,	ALTMON_9, "" },
-	{ "altmon_10",		1, LC_TIME,	ALTMON_10, "" },
-	{ "altmon_11",		1, LC_TIME,	ALTMON_11, "" },
-	{ "altmon_12",		1, LC_TIME,	ALTMON_12, "" },
+	{ "altmon_1",		1, LC_TIME,	ALTMON_1, "(FreeBSD only)" },
+	{ "altmon_2",		1, LC_TIME,	ALTMON_2, "(FreeBSD only)" },
+	{ "altmon_3",		1, LC_TIME,	ALTMON_3, "(FreeBSD only)" },
+	{ "altmon_4",		1, LC_TIME,	ALTMON_4, "(FreeBSD only)" },
+	{ "altmon_5",		1, LC_TIME,	ALTMON_5, "(FreeBSD only)" },
+	{ "altmon_6",		1, LC_TIME,	ALTMON_6, "(FreeBSD only)" },
+	{ "altmon_7",		1, LC_TIME,	ALTMON_7, "(FreeBSD only)" },
+	{ "altmon_8",		1, LC_TIME,	ALTMON_8, "(FreeBSD only)" },
+	{ "altmon_9",		1, LC_TIME,	ALTMON_9, "(FreeBSD only)" },
+	{ "altmon_10",		1, LC_TIME,	ALTMON_10, "(FreeBSD only)" },
+	{ "altmon_11",		1, LC_TIME,	ALTMON_11, "(FreeBSD only)" },
+	{ "altmon_12",		1, LC_TIME,	ALTMON_12, "(FreeBSD only)" },
 	{ "era",		1, LC_TIME,	ERA, "(unavailable)" },
 	{ "era_d_fmt",		1, LC_TIME,	ERA_D_FMT, "(unavailable)" },
 	{ "era_d_t_fmt",	1, LC_TIME,	ERA_D_T_FMT, "(unavailable)" },