diff --git a/lib/stdio/vfscanf.c b/lib/stdio/vfscanf.c
index b2a63d7a..a9fdba87 100644
--- a/lib/stdio/vfscanf.c
+++ b/lib/stdio/vfscanf.c
@@ -23,6 +23,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <ctype.h>
 
 int
 vfscanf (FILE * stream, char const *template, va_list ap)