diff --git a/mrbgems/mruby-eval/src/eval.c b/mrbgems/mruby-eval/src/eval.c
index d849bb872..06baad531 100644
--- a/mrbgems/mruby-eval/src/eval.c
+++ b/mrbgems/mruby-eval/src/eval.c
@@ -178,8 +178,7 @@ mrb_value mrb_obj_instance_eval(mrb_state *mrb, mrb_value self);
 static mrb_value
 f_instance_eval(mrb_state *mrb, mrb_value self)
 {
-  mrb_value b, ret;
-  struct RClass *c;
+  mrb_value b;
   mrb_int argc; mrb_value *argv;
 
   mrb_get_args(mrb, "*&", &argv, &argc, &b);