diff -ur fireflies-2.07.orig/src/vroot.h fireflies-2.07/src/vroot.h
--- fireflies-2.07.orig/src/vroot.h	2005-12-09 05:07:30.000000000 +0200
+++ fireflies-2.07/src/vroot.h	2009-08-09 21:18:40.000000000 +0300
@@ -78,6 +78,8 @@
  "#Id: vroot.h,v 1.4 1991/09/30 19:23:16 stolcke Exp stolcke #";
 #endif
 
+#include <stdio.h>
+
 #include <X11/X.h>
 #include <X11/Xatom.h>
 #include <X11/Xlib.h>