diff --git a/lib/stdio/vfscanf.c b/lib/stdio/vfscanf.c
index 33b47a1b..1aa2d169 100644
--- a/lib/stdio/vfscanf.c
+++ b/lib/stdio/vfscanf.c
@@ -1,6 +1,7 @@
 /* -*-comment-start: "//";comment-end:""-*-
  * GNU Mes --- Maxwell Equations of Software
  * Copyright © 2017,2018,2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+ * Copyright © 2019 Danny Milosavljevic <dannym@scratchpost.org>
  *
  * This file is part of GNU Mes.
  *
@@ -24,6 +25,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <ctype.h>
 
 int
 vfscanf (FILE * stream, char const *template, va_list ap)