diff --git a/dotenv-rails-safe.gemspec b/dotenv-rails-safe.gemspec
index fbb8fb9..e0bfbcb 100644
--- a/dotenv-rails-safe.gemspec
+++ b/dotenv-rails-safe.gemspec
@@ -39,7 +39,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "bundler", "~> 1.13"
   spec.add_development_dependency "rake", "~> 10.0"
   spec.add_development_dependency "rspec", "~> 3.0"
-  spec.add_development_dependency "rails", "~> 4.0"
+  spec.add_development_dependency "rails", "~> 5.2"
   spec.add_development_dependency "coveralls"
   spec.add_development_dependency "pry"
   spec.add_development_dependency "bump"