Index: twm.c
--- twm.c.orig
+++ twm.c
@@ -93,6 +93,7 @@ static char RCSinfo[] =
 #endif
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <signal.h>
 #include <fcntl.h>
 #include "twm.h"
@@ -108,6 +109,7 @@ static char RCSinfo[] =
 #include "screen.h"
 #include "iconmgr.h"
 #include <X11/Xproto.h>
+#include <X11/Xmu/Error.h>
 #include <X11/bitmaps/root_weave>
 #include "vdt.h"
 #define XK_LATIN1