--- a/codemirror-rails.gemspec
+++ b/codemirror-rails.gemspec
@@ -1,4 +1,4 @@
-require File.expand_path('../lib/codemirror/rails/version', __FILE__)
+require './lib/codemirror/rails/version'

 Gem::Specification.new do |s|
   s.name        = "codemirror-rails"
@@ -13,4 +13,4 @@
   s.files = Dir.glob('{doc,lib,vendor}/**/*') + %w(LICENSE README.md)

-  s.add_runtime_dependency 'railties', '>= 3.0', '< 6.0'
+  s.add_runtime_dependency 'railties', '>= 3.0', '< 8.1'