1 files changed, 1 insertions, 1 deletions
diff --git a/src/kernel.c b/src/kernel.c
index 1040dbe05..240c0dcb3 100644
--- a/src/kernel.c
+++ b/src/kernel.c
@@ -1038,7 +1038,7 @@ mrb_obj_remove_instance_variable(mrb_state *mrb, mrb_value self)
 
   mrb_get_args(mrb, "n", &sym);
   val = mrb_iv_remove(mrb, self, sym);
-  if (UNDEF_P(val)) {
+  if (mrb_undef_p(val)) {
     mrb_name_error(mrb, sym, "instance variable %s not defined", mrb_sym2name(mrb, sym));
   }
   return val;