diff --git a/contrib/tzcode/localtime.c b/contrib/tzcode/localtime.c
--- a/contrib/tzcode/localtime.c
+++ b/contrib/tzcode/localtime.c
@@ -1517,9 +1517,8 @@
 }
 
 static void
-tzset_unlocked(void)
+tzset_unlocked_name(char const *name)
 {
-  char const *name = getenv("TZ");
   struct state *sp = lclptr;
   int lcl = name ? strlen(name) < sizeof lcl_TZname : -1;
   if (lcl < 0
@@ -1541,6 +1540,12 @@
   lcl_is_set = lcl;
 }
 
+static void
+tzset_unlocked(void)
+{
+  tzset_unlocked_name(getenv("TZ"));
+}
+
 void
 tzset(void)
 {
@@ -1550,6 +1555,18 @@
   unlock();
 }
 
+void
+freebsd13_tzsetwall(void)
+{
+  if (lock() != 0)
+    return;
+  tzset_unlocked_name(NULL);
+  unlock();
+}
+__sym_compat(tzsetwall, freebsd13_tzsetwall, FBSD_1.0);
+__warn_references(tzsetwall,
+    "warning: tzsetwall() is deprecated, use tzset() instead.");
+
 static void
 gmtcheck(void)
 {
diff --git a/lib/libc/gen/tzset.3 b/lib/libc/gen/tzset.3
--- a/lib/libc/gen/tzset.3
+++ b/lib/libc/gen/tzset.3
@@ -31,7 +31,7 @@
 .\"	@(#)tzset.3	8.2 (Berkeley) 11/17/93
 .\" $FreeBSD$
 .\"
-.Dd November 17, 1993
+.Dd February 8, 2023
 .Dt TZSET 3
 .Os
 .Sh NAME
@@ -102,10 +102,14 @@
 .Pp
 The
 .Fn tzsetwall
-function
-sets things up so that
-.Xr localtime 3
-returns the best available approximation of local wall clock time.
+function is equivalent to calling
+.Fn tzset
+with the
+.Ev TZ
+environment variable unset.
+It is deprecated and may not be available in
+.Fx 14.0
+and later.
 .Sh SPECIFICATION FORMAT
 When
 .Ev TZ