diff --git a/interpreters/glulxe/serial.c b/interpreters/glulxe/serial.c
index 2ce4908..63a4cd9 100644
--- a/interpreters/glulxe/serial.c
+++ b/interpreters/glulxe/serial.c
@@ -89,11 +89,14 @@ int init_serial()
   return TRUE;
 }
 
+#include <stdio.h>
+
 /* final_serial():
    Clean up memory when the VM shuts down.
 */
 void final_serial()
 {
+  fprintf(stderr, "-----\nfinal_serial undo_chain=%p\n-----\n", undo_chain);
   if (undo_chain) {
     int ix;
     for (ix=0; ix<undo_chain_num; ix++) {
@@ -202,6 +205,7 @@ glui32 perform_saveundo()
     if (undo_chain_num < undo_chain_size)
       undo_chain_num += 1;
     dest.ptr = NULL;
+    fprintf(stderr, "-----\nsuccessful perform_saveundo\n-----\n");
   }
   else {
     /* It didn't work. */