diff --git a/sysdep/unix/config.Y b/sysdep/unix/config.Y
index af35f82e..5176be62 100644
--- a/sysdep/unix/config.Y
+++ b/sysdep/unix/config.Y
@@ -9,6 +9,7 @@
 CF_HDR
 
 #include "lib/unix.h"
+#include <stdio.h>
 
 CF_DECLS