Index: src/tclx/tkucbsrc/tkevent.sed
--- src/tclx/tkucbsrc/tkevent.sed.orig
+++ src/tclx/tkucbsrc/tkevent.sed
@@ -1,4 +1,5 @@
 /#include <signal.h>/a\
+#include "tclxtend.h"\
 extern Tcl_Interp *tk_mainInterp;
 
 /numFound = select(numFds/i\
