--- ../tty_aux.c.orig	2021-09-22 11:12:35.845952747 +0200
+++ ./tty_aux.c	2021-09-22 11:13:47.397197243 +0200
@@ -121,7 +121,7 @@
 
 #if !defined(HAVE_STRUCT_TERMIOS) && !defined(HAVE_STRUCT_TERMIO)
 # include <sgtty.h>
-struct sgttyb oldsb, newsb;
+extern struct sgttyb oldsb, newsb;
 void hangup();
 #else
 # ifndef HAVE_STRUCT_TERMIOS
@@ -131,7 +131,7 @@
 #  ifdef HAVE_SYS_TERMIO_H
 #   include <sys/termio.h>
 #  endif
-struct termio oldsb, newsb;
+extern struct termio oldsb, newsb;
 # else
 #  ifdef HAVE_TERMIOS_H
 #   include <termios.h>
@@ -139,7 +139,7 @@
 #  ifdef HAVE_SYS_TERMIOS_H
 #   include <sys/termios.h>
 #  endif
-struct termios oldsb, newsb;
+extern struct termios oldsb, newsb;
 # endif
 # ifndef NCC
 #  define NCC NCCS