diff --git a/.travis.yml b/.travis.yml
index 1e55bbe..062f3cb 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,8 +1,9 @@
 language: ruby
 before_install: gem install bundler -v '<2'
 rvm:
+  - 2.7
   - 2.6
   - 2.5
-  - 2.0
+  - 2.3
 script:
   - bundle exec rspec
diff --git a/CHANGELOG.md b/CHANGELOG.md
index a9ef64f..1c7a5de 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,12 @@
 ### Changelog
 
+### 6.0.0
+
+- Dropping support for Ruby <2.3 (Major version bump)
+- Fix issue when using --enable-frozen-string-literal Ruby option #95 (jeremyevans)
+- Update gems (rake, addressable)
+- Update Travis tests to include Ruby 2.7
+
 ### 5.1.0
 
 - Create `random_base32` to perform `random` to avoid breaking changes
diff --git a/Dockerfile-2.3 b/Dockerfile-2.3
new file mode 100644
index 0000000..10a3a52
--- /dev/null
+++ b/Dockerfile-2.3
@@ -0,0 +1,10 @@
+FROM ruby:2.3
+
+RUN mkdir -p /usr/src/app
+WORKDIR /usr/src/app
+
+COPY Gemfile /usr/src/app/
+COPY . /usr/src/app
+RUN bundle install
+
+CMD ["bundle", "exec", "rspec"]
diff --git a/Dockerfile-2.0 b/Dockerfile-2.7
similarity index 91%
rename from Dockerfile-2.0
rename to Dockerfile-2.7
index 3af3083..3f53cf6 100644
--- a/Dockerfile-2.0
+++ b/Dockerfile-2.7
@@ -1,4 +1,4 @@
-FROM ruby:2.0
+FROM ruby:2.7
 
 RUN mkdir -p /usr/src/app
 WORKDIR /usr/src/app
diff --git a/lib/rotp/base32.rb b/lib/rotp/base32.rb
index 1688bdb..2c09592 100644
--- a/lib/rotp/base32.rb
+++ b/lib/rotp/base32.rb
@@ -28,7 +28,7 @@ def decode(str)
 
       def encode(b)
         data = b.unpack('c*')
-        out = ''
+        out = String.new
         buffer = data[0]
         idx = 1
         bits_left = 8
diff --git a/lib/rotp/version.rb b/lib/rotp/version.rb
index 25a33f1..b79f7ff 100644
--- a/lib/rotp/version.rb
+++ b/lib/rotp/version.rb
@@ -1,3 +1,3 @@
 module ROTP
-  VERSION = '5.1.0'.freeze
+  VERSION = '6.0.0'.freeze
 end
diff --git a/rotp.gemspec b/rotp.gemspec
index e320466..050fedf 100644
--- a/rotp.gemspec
+++ b/rotp.gemspec
@@ -4,6 +4,7 @@ Gem::Specification.new do |s|
   s.name        = 'rotp'
   s.version     = ROTP::VERSION
   s.platform    = Gem::Platform::RUBY
+  s.required_ruby_version = '~> 2.3'
   s.license     = 'MIT'
   s.authors     = ['Mark Percival']
   s.email       = ['mark@markpercival.us']
@@ -16,9 +17,9 @@ Gem::Specification.new do |s|
   s.executables   = `git ls-files -- bin/*`.split("\n").map { |f| File.basename(f) }
   s.require_paths = ['lib']
 
-  s.add_runtime_dependency 'addressable', '~> 2.5'
+  s.add_runtime_dependency 'addressable', '~> 2.7'
 
-  s.add_development_dependency 'rake', '~> 10.5'
+  s.add_development_dependency "rake", "~> 13.0"
   s.add_development_dependency 'rspec', '~> 3.5'
   s.add_development_dependency 'simplecov', '~> 0.12'
   s.add_development_dependency 'timecop', '~> 0.8'