diff --git a/lib/unicode_normalize.rb b/lib/unicode_normalize.rb
deleted file mode 100644
index b518197706..0000000000
--- a/lib/unicode_normalize.rb
+++ /dev/null
@@ -1,11 +0,0 @@
-# coding: utf-8
-# frozen_string_literal: false
-
-# Copyright Ayumu Nojima (野島 歩) and Martin J. Dürst (duerst@it.aoyama.ac.jp)
-
-#--
-# additions to class String for Unicode normalization
-#++
-
-###### This file is empty after it's contents has been converted to C
-###### and moved to string.c. This file will be removed soon.