diff -p -up fireflies-2.07/src/vroot.h~ fireflies-2.07/src/vroot.h
--- fireflies-2.07/src/vroot.h~	2005-12-09 04:07:30.000000000 +0100
+++ fireflies-2.07/src/vroot.h	2009-07-28 10:14:10.000000000 +0200
@@ -82,6 +82,8 @@ static const char vroot_rcsid[] =
 #include <X11/Xatom.h>
 #include <X11/Xlib.h>
 
+#include <stdio.h>
+
 static Window
 #ifdef __STDC__ /* ANSIfication added by jwz, to avoid superfluous warnings. */
 VirtualRootWindowOfScreen(Screen *screen)