diff -urN ../exim-4.89.1.orig/OS/os.h-FreeBSD ./OS/os.h-FreeBSD
--- ../exim-4.89.1.orig/OS/os.h-FreeBSD	2017-11-28 23:40:59.000000000 +0200
+++ ./OS/os.h-FreeBSD	2018-01-14 15:58:43.095640000 +0200
@@ -29,7 +29,7 @@
  * which makes the libiconv try to not interfere with OS iconv.
  */
 #if __FreeBSD__ >= 10
-# define LIBICONV_PLUG
+//# define LIBICONV_PLUG
 #endif
 /* for more specific version constraints, include <sys/param.h> and look at
  * __FreeBSD_version */