mpdm_f.c:1947:9: error: use of undeclared identifier 'environ'
        environ = (char **) calloc(sizeof(char *), mpdm_size(v) + 1);

--- mpdm/mpdm_f.c.orig	2020-11-22 08:58:48 UTC
+++ mpdm/mpdm_f.c
@@ -78,6 +78,8 @@
 #include <sys/file.h>
 #endif
 
+#include <netinet/in.h>
+
 #include "mpdm.h"
 
 #ifdef CONFOPT_ICONV
@@ -1974,6 +1976,7 @@ static int sysdep_popen(mpdm_t v, char *prg, int rw)
 
         /* build the environment for the subprocess */
         v = mpdm_join(mpdm_get_wcs(mpdm_root(), L"ENV"), MPDM_S(L"="));
+        extern char **environ;
         environ = (char **) calloc(sizeof(char *), mpdm_size(v) + 1);
 
         mpdm_ref(v);