diff --git a/src/xschem.h b/src/xschem.h
index 97910452..01ec5382 100644
--- a/src/xschem.h
+++ b/src/xschem.h
@@ -123,6 +123,7 @@ extern char win_temp_dir[PATH_MAX];
 #include <tcl.h>
 #include <tk.h>
 
+#define _ALLOC_ID_ 0 /* to be replaced with unique IDs in my_*() allocations for memory tracking */
 #define CADHEIGHT 700                   /*  initial window size */
 #define CADWIDTH 1000