https://bugs.gentoo.org/706880
--- a/src/editor.c
+++ b/src/editor.c
@@ -24,7 +24,7 @@
 #include "common.h"
 #include "proto.h"
 
-char map[MAP_YSIZE][MAP_XSIZE];
+extern char map[MAP_YSIZE][MAP_XSIZE];
 int lock;
 int last_obj;
 
--- a/src/frame.c
+++ b/src/frame.c
@@ -26,7 +26,7 @@ void bail(char *message);
 void sigint_handler();
 void sigwinch_handler();
 
-int need_refresh;
+extern int need_refresh;
 
 void curses_start(void)
 {