diff --git a/src/vm.c b/src/vm.c
index db4ca5cba..f5405b003 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -2434,6 +2434,7 @@ mrb_top_run(mrb_state *mrb, struct RProc *proc, mrb_value self, unsigned int sta
     return mrb_vm_run(mrb, proc, self, stack_keep);
   }
   ci = cipush(mrb);
+  ci->mid = 0;
   ci->nregs = 1;   /* protect the receiver */
   ci->acc = CI_ACC_SKIP;
   ci->target_class = mrb->object_class;