diff --git a/src/gc.c b/src/gc.c
index f4186f6e3..ad5bcc7a8 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -401,8 +401,8 @@ obj_free(mrb_state *mrb, struct RBasic *obj)
       struct REnv *e = (struct REnv *)obj;
 
       if (e->cioff < 0) {
-	mrb_free(mrb, mrb->stack);
-	mrb->stack = 0;
+	mrb_free(mrb, e->stack);
+	e->stack = 0;
       }
     }
     break;