Index: Widgets/util.c
--- Widgets/util.c.orig
+++ Widgets/util.c
@@ -27,6 +27,7 @@
  *          University of Newcastle upon Tyne, UK
  */
 
+#include <unistd.h>
 #include <X11/Intrinsic.h>
 #include <X11/StringDefs.h>