--- interface/tk_c.c.orig	2009-02-09 17:57:06.000000000 -0200
+++ interface/tk_c.c	2009-02-09 18:06:22.000000000 -0200
@@ -50,6 +50,8 @@
 #include <sys/ipc.h>
 #include <sys/shm.h>
 #include <sys/sem.h>
+// Legacy code need this definition -> see man page for TclInterp
+#define USE_INTERP_RESULT
 #include <tcl.h>
 #include <tk.h>
 #include <sys/wait.h>