diff --git a/mrbgems/mruby-fiber/src/fiber.c b/mrbgems/mruby-fiber/src/fiber.c
index c98dd0e67..5be2095f7 100644
--- a/mrbgems/mruby-fiber/src/fiber.c
+++ b/mrbgems/mruby-fiber/src/fiber.c
@@ -169,7 +169,7 @@ fiber_resume(mrb_state *mrb, mrb_value self)
     while (b<e) {
       *b++ = *a++;
     }
-    c->ci->argc = len;
+    c->cibase->argc = len;
     c->prev = mrb->c;
     c->status = MRB_FIBER_RUNNING;
     mrb->c = c;