diff --git a/include/picrin/error.h b/include/picrin/error.h
index cebc85e1..1c62294f 100644
--- a/include/picrin/error.h
+++ b/include/picrin/error.h
@@ -41,6 +41,7 @@ struct pic_error {
   } type;
   struct pic_string *msg;
   pic_value irrs;
+  pic_str *stack;
 };
 
 #define pic_error_p(v) (pic_type(v) == PIC_TT_ERROR)
diff --git a/src/debug.c b/src/debug.c
index 63bc88a0..7ce89fc0 100644
--- a/src/debug.c
+++ b/src/debug.c
@@ -65,7 +65,7 @@ pic_print_backtrace(pic_state *pic, struct pic_error *e)
   /* TODO: print error irritants */
 
   trace = pic_strcat(pic, trace, pic_str_new(pic, "\n", 1));
-  trace = pic_strcat(pic, trace, pic_get_backtrace(pic));
+  trace = pic_strcat(pic, trace, e->stack);
 
   /* print! */
   printf("%s", pic_str_cstr(trace));
diff --git a/src/error.c b/src/error.c
index 227c80f3..2c319b79 100644
--- a/src/error.c
+++ b/src/error.c
@@ -96,6 +96,7 @@ pic_errorf(pic_state *pic, const char *fmt, ...)
   e->type = PIC_ERROR_OTHER;
   e->msg = pic_str_ptr(pic_car(pic, err_line));
   e->irrs = pic_cdr(pic, err_line);
+  e->stack = pic_get_backtrace(pic);
 
   pic_throw(pic, e);
 }
@@ -133,6 +134,7 @@ pic_error_raise(pic_state *pic)
   e->type = PIC_ERROR_RAISED;
   e->msg = pic_str_new_cstr(pic, "object is raised");
   e->irrs = pic_list1(pic, v);
+  e->stack = pic_get_backtrace(pic);
 
   pic_throw(pic, e);
 }
@@ -151,6 +153,7 @@ pic_error_error(pic_state *pic)
   e->type = PIC_ERROR_OTHER;
   e->msg = str;
   e->irrs = pic_list_by_array(pic, argc, argv);
+  e->stack = pic_get_backtrace(pic);
 
   pic_throw(pic, e);
 }
diff --git a/src/gc.c b/src/gc.c
index 81906f66..fd48833e 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -391,6 +391,7 @@ gc_mark_object(pic_state *pic, struct pic_object *obj)
     struct pic_error *err = (struct pic_error *)obj;
     gc_mark_object(pic,(struct pic_object *)err->msg);
     gc_mark(pic, err->irrs);
+    gc_mark_object(pic, (struct pic_object *)err->stack);
     break;
   }
   case PIC_TT_STRING: {