diff --git a/.travis.yml b/.travis.yml
index 2dff396..0e6fc88 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,7 @@
 sudo: false
 language: ruby
 rvm:
-  - 2.3.5
-  - 2.4.2
-before_install: gem install bundler -v 1.16.0
+  - 2.3.6
+  - 2.4.3
+  - 2.5.0
+before_install: gem install bundler -v 1.16.1
diff --git a/keisan.gemspec b/keisan.gemspec
index 2afde4c..fa4d6f5 100644
--- a/keisan.gemspec
+++ b/keisan.gemspec
@@ -19,7 +19,7 @@ Gem::Specification.new do |spec|
   end
   spec.require_paths = ["lib"]
 
-  spec.required_ruby_version = ">= 2.0.0"
+  spec.required_ruby_version = ">= 2.3.0"
 
   spec.add_development_dependency "coveralls"
   spec.add_development_dependency "bundler", "~> 1.14"