diff --git a/include/stdio.h b/include/stdio.h
index de11d350..825ae88e 100644
--- a/include/stdio.h
+++ b/include/stdio.h
@@ -78,6 +78,7 @@ int putchar (int c);
 int puts (char const *s);
 int remove (char const *file_name);
 void rewind (FILE * stream);
+void setbuf (FILE *stream, char *buf);
 int setvbuf (FILE * stream, char *buf, int mode, size_t size);
 int ungetc (int c, FILE * stream);
 long ftell (FILE * stream);
diff --git a/lib/stub/setbuf.c b/lib/stub/setbuf.c
index b038600a..38af4477 100644
--- a/lib/stub/setbuf.c
+++ b/lib/stub/setbuf.c
@@ -1,6 +1,6 @@
 /* -*-comment-start: "//";comment-end:""-*-
  * GNU Mes --- Maxwell Equations of Software
- * Copyright © 2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+ * Copyright © 2018,2022 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
  *
  * This file is part of GNU Mes.
  *
@@ -20,14 +20,14 @@
 
 #include <mes/lib.h>
 #include <errno.h>
+#include <stdio.h>
 
-int
-setbuf (int x)
+void
+setbuf (FILE *stream, char *buf)
 {
   static int stub = 0;
   if (__mes_debug () && !stub)
     eputs ("setbuf stub\n");
   stub = 1;
   errno = 0;
-  return 0;
 }