diff -ruN /usr/ports/net/shadowsocks-libev/files/patch-libcork_src_libcork_posix_env.c ./shadowsocks-libev/files/patch-libcork_src_libcork_posix_env.c
--- /usr/ports/net/shadowsocks-libev/files/patch-libcork_src_libcork_posix_env.c	1970-01-01 00:00:00.000000000 +0000
+++ ./shadowsocks-libev/files/patch-libcork_src_libcork_posix_env.c	2021-11-21 00:49:15.850285000 +0000
@@ -0,0 +1,22 @@
+--- libcork/src/libcork/posix/env.c.orig	2019-07-24 14:01:14 UTC
++++ libcork/src/libcork/posix/env.c
+@@ -194,12 +194,19 @@ cork_env_set_vars(void *user_data, struct cork_hash_ta
+  *
+  * [1] http://www.gnu.org/software/gnulib/manual/html_node/clearenv.html
+  */
++
++#if (defined(__FreeBSD__) && (__FreeBSD__ < 14))
++/* Since FreeBSD 14.0-CURRENT, the clearenv(3) function was added to stdlib.
++ * See https://reviews.freebsd.org/R10:597b02675751e48dd04777f1e91fee382bf3a966
++ */
++
+ static void
+ clearenv(void)
+ {
+     *environ = NULL;
+ }
+ 
++#endif
+ #else
+ /* Otherwise assume that we have clearenv available. */
+ #endif