https://bugs.gentoo.org/557322
This is only way to make this compile with C99 and up:
Force cast one opaque pointer type to another.
--- a/crs.c
+++ b/crs.c
@@ -69,8 +69,8 @@
   bwaddch,
   bwaddstr,
   bwwrite,
-  wrefresh,
-  wgetch,
+  (int (*)(FILE *))wrefresh,
+  (int (*)(FILE *))wgetch,
   freewindow};
 
 SCM mkwindow(win)