diff --git a/gc.c b/gc.c
index db840f1b05..1840edb024 100644
--- a/gc.c
+++ b/gc.c
@@ -11666,7 +11666,7 @@ rb_raw_obj_info(char *buff, const int buff_size, VALUE obj)
 
                     if (me->def->type == VM_METHOD_TYPE_ISEQ) {
                         // APPENDF((BUFF_ARGS, " (iseq:%p)", (void *)me->def->body.iseq.iseqptr));
-                        APPENDF((BUFF_ARGS, " (iseq:%s)", obj_info(me->def->body.iseq.iseqptr)));
+                        APPENDF((BUFF_ARGS, " (iseq:%s)", obj_info((VALUE)me->def->body.iseq.iseqptr)));
                     }
 		}
 		else {