--- err.c.orig	2014-07-11 00:19:30.000000000 +0900
+++ err.c	2020-02-28 21:59:11.000000000 +0900
@@ -47,7 +47,7 @@
 
 #ifdef __STDC__
 #include <stdarg.h>
-extern vfprintf (FILE *, const char *, va_list);
+extern int vfprintf (FILE *, const char *, va_list);
 #else /* ! __STDC__ */
 #include <varargs.h>
 extern vfprintf ();