diff --git a/src/xinit.c b/src/xinit.c
index b7eaa499..3f4f1294 100644
--- a/src/xinit.c
+++ b/src/xinit.c
@@ -586,6 +586,11 @@ void alloc_xschem_data(const char *top_path)
   xctx->undo_initialized = 0; /* in_memory_undo */
   #endif
   xctx->time_last_modify = 0;
+  xctx->push_undo_ptr = &push_undo;
+  xctx->pop_undo_ptr = &pop_undo;
+  xctx->delete_undo_ptr = &delete_undo;
+  xctx->clear_undo_ptr = &clear_undo;
+
 }
 
 void delete_schematic_data(void)
diff --git a/src/xschem.h b/src/xschem.h
index 958ec499..35f29311 100644
--- a/src/xschem.h
+++ b/src/xschem.h
@@ -713,6 +713,10 @@ typedef struct {
   int fill_pattern;
   int draw_window; 
   time_t time_last_modify;
+  void (*push_undo_ptr)(void);
+  void (*pop_undo_ptr)(int, int);
+  void (*delete_undo_ptr)(void);
+  void (*clear_undo_ptr)(void);
 } Xschem_ctx;
 
 struct Lcc { /* used for symbols containing schematics as instances (LCC, Local Custom Cell) */