diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 78498f64..9ebb95ed 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -12,25 +12,11 @@ jobs:
       matrix:
         ruby: ['2.5', '2.6', '2.7', '3.0', '3.1', head, jruby-head]
         os: [ubuntu-latest, windows-latest]
-        gemfile: [cucumber_4, cuke_modeler_3_minimum, cuke_modeler_3]
         task: [spec]
         include:
           - ruby: '2.5' # lowest supported version
             os: ubuntu-latest
-            gemfile: cuke_modeler_3 # Any one of the gemfiles should be fine
             task: rubocop
-        exclude:
-          # CukeModeler 3.x does not support Ruby 3 until CM 3.6
-          - gemfile: cuke_modeler_3_minimum
-            ruby: jruby-head
-          - gemfile: cuke_modeler_3_minimum
-            ruby: head
-          - gemfile: cuke_modeler_3_minimum
-            ruby: '3.1'
-          - gemfile: cuke_modeler_3_minimum
-            ruby: '3.0'
-    env: # $BUNDLE_GEMFILE must be set at the job level, so that it is set for all steps
-      BUNDLE_GEMFILE: ci_gemfiles/${{ matrix.gemfile }}.gemfile
     steps:
     - uses: actions/checkout@master
     - uses: ruby/setup-ruby@v1
diff --git a/.rubocop.yml b/.rubocop.yml
index 67bb29d8..7c49c081 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -128,3 +128,7 @@ Style/CaseEquality:
 
 Lint/EmptyClass:
   Enabled: false
+
+# ENV.fetch('FOO', nil) is the same as ENV['FOO']
+Style/FetchEnvVar:
+  Enabled: false
diff --git a/Gemfile b/Gemfile
index df643bd9..5392e329 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,4 +5,10 @@ gemspec
 gem 'bump'
 gem 'test-unit'
 gem 'minitest', '~> 5.5.0'
+gem 'rspec', '~> 3.3'
+gem 'cucumber', "~> 4.0"
+gem 'cuke_modeler', '~> 3.6'
 gem 'spinach', git: "https://github.com/grosser/spinach.git", branch: "grosser/json" # https://github.com/codegram/spinach/pull/229
+gem 'rake'
+gem 'rubocop', '~> 1.28.0' # lock minor so we do not get accidental violations, also need to drop ruby 2.5 support to upgrade further
+gem 'rubocop-ast', '~> 1.17.0' # also need to drop ruby 2.5 support to remove this line
diff --git a/Gemfile.lock b/Gemfile.lock
index e61c4be6..cf6b17a0 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -66,7 +66,6 @@ GEM
     gherkin-ruby (0.3.2)
     i18n (1.10.0)
       concurrent-ruby (~> 1.0)
-    json (2.6.2)
     middleware (0.1.0)
     minitest (5.5.1)
     multi_test (0.1.2)
@@ -96,17 +95,16 @@ GEM
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.11.0)
     rspec-support (3.11.0)
-    rubocop (1.35.1)
-      json (~> 2.3)
+    rubocop (1.28.2)
       parallel (~> 1.10)
-      parser (>= 3.1.2.1)
+      parser (>= 3.1.0.0)
       rainbow (>= 2.2.2, < 4.0)
       regexp_parser (>= 1.8, < 3.0)
-      rexml (>= 3.2.5, < 4.0)
-      rubocop-ast (>= 1.20.1, < 2.0)
+      rexml
+      rubocop-ast (>= 1.17.0, < 2.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 1.4.0, < 3.0)
-    rubocop-ast (1.21.0)
+    rubocop-ast (1.17.0)
       parser (>= 3.1.1.0)
     ruby-progressbar (1.11.0)
     sys-uname (1.2.2)
@@ -127,14 +125,15 @@ PLATFORMS
 DEPENDENCIES
   bump
   cucumber (~> 4.0)
-  cuke_modeler (~> 3.0)
+  cuke_modeler (~> 3.6)
   minitest (~> 5.5.0)
   parallel_tests!
   rake
   rspec (~> 3.3)
-  rubocop
+  rubocop (~> 1.28.0)
+  rubocop-ast (~> 1.17.0)
   spinach!
   test-unit
 
 BUNDLED WITH
-   2.3.6
+   2.3.7
diff --git a/Rakefile b/Rakefile
index 1409b9f1..d184aff7 100644
--- a/Rakefile
+++ b/Rakefile
@@ -19,7 +19,7 @@ end
 
 desc "bundle all gemfiles [EXTRA=]"
 task :bundle_all do
-  extra = ENV.fetch("EXTRA", nil) || "install"
+  extra = ENV["EXTRA"] || "install"
 
   gemfiles = (["Gemfile"] + Dir["spec/fixtures/rails*/Gemfile"])
   raise if gemfiles.size < 3
diff --git a/ci_gemfiles/cucumber_4.gemfile b/ci_gemfiles/cucumber_4.gemfile
deleted file mode 100644
index fe582868..00000000
--- a/ci_gemfiles/cucumber_4.gemfile
+++ /dev/null
@@ -1,11 +0,0 @@
-# frozen_string_literal: true
-source 'https://rubygems.org'
-gemspec path: "../"
-
-gem 'bump'
-gem 'test-unit'
-gem 'minitest', '~> 5.5.0'
-gem 'spinach', git: "https://github.com/grosser/spinach.git", branch: "grosser/json" # https://github.com/codegram/spinach/pull/229
-
-# The version of Cucumber being tested
-gem 'cucumber', '~> 4.0'
diff --git a/ci_gemfiles/cuke_modeler_3.gemfile b/ci_gemfiles/cuke_modeler_3.gemfile
deleted file mode 100644
index 6b817538..00000000
--- a/ci_gemfiles/cuke_modeler_3.gemfile
+++ /dev/null
@@ -1,11 +0,0 @@
-# frozen_string_literal: true
-source 'https://rubygems.org'
-gemspec path: "../"
-
-gem 'bump'
-gem 'test-unit'
-gem 'minitest', '~> 5.5.0'
-gem 'spinach', git: "https://github.com/grosser/spinach.git", branch: "grosser/json" # https://github.com/codegram/spinach/pull/229
-
-# The version of CukeModeler being tested
-gem 'cuke_modeler', '~> 3.0'
diff --git a/ci_gemfiles/cuke_modeler_3_minimum.gemfile b/ci_gemfiles/cuke_modeler_3_minimum.gemfile
deleted file mode 100644
index 29440976..00000000
--- a/ci_gemfiles/cuke_modeler_3_minimum.gemfile
+++ /dev/null
@@ -1,11 +0,0 @@
-# frozen_string_literal: true
-source 'https://rubygems.org'
-gemspec path: "../"
-
-gem 'bump'
-gem 'test-unit'
-gem 'minitest', '~> 5.5.0'
-gem 'spinach', git: "https://github.com/grosser/spinach.git", branch: "grosser/json" # https://github.com/codegram/spinach/pull/229
-
-# The version of CukeModeler being tested
-gem 'cuke_modeler', '3.0.0'
diff --git a/lib/parallel_tests.rb b/lib/parallel_tests.rb
index b96162be..356ba7ef 100644
--- a/lib/parallel_tests.rb
+++ b/lib/parallel_tests.rb
@@ -16,7 +16,7 @@ class << self
     def determine_number_of_processes(count)
       [
         count,
-        ENV.fetch("PARALLEL_TEST_PROCESSORS", nil),
+        ENV["PARALLEL_TEST_PROCESSORS"],
         Parallel.processor_count
       ].detect { |c| !c.to_s.strip.empty? }.to_i
     end
@@ -68,8 +68,8 @@ def first_process?
     end
 
     def last_process?
-      current_process_number = ENV.fetch('TEST_ENV_NUMBER', nil)
-      total_processes = ENV.fetch('PARALLEL_TEST_GROUPS', nil)
+      current_process_number = ENV['TEST_ENV_NUMBER']
+      total_processes = ENV['PARALLEL_TEST_GROUPS']
       return true if current_process_number.nil? && total_processes.nil?
       current_process_number = '1' if current_process_number.nil?
       current_process_number == total_processes
diff --git a/lib/parallel_tests/cli.rb b/lib/parallel_tests/cli.rb
index 96daa323..5c3e1864 100644
--- a/lib/parallel_tests/cli.rb
+++ b/lib/parallel_tests/cli.rb
@@ -383,7 +383,7 @@ def use_colors?
     end
 
     def first_is_1?
-      val = ENV.fetch("PARALLEL_TEST_FIRST_IS_1", nil)
+      val = ENV["PARALLEL_TEST_FIRST_IS_1"]
       ['1', 'true'].include?(val)
     end
 
@@ -391,7 +391,7 @@ def first_is_1?
     def simulate_output_for_ci(simulate)
       if simulate
         progress_indicator = Thread.new do
-          interval = Float(ENV.fetch('PARALLEL_TEST_HEARTBEAT_INTERVAL', 60))
+          interval = Float(ENV['PARALLEL_TEST_HEARTBEAT_INTERVAL'] || 60)
           loop do
             sleep interval
             print '.'
diff --git a/lib/parallel_tests/cucumber/scenarios.rb b/lib/parallel_tests/cucumber/scenarios.rb
index 6c95998f..7f9b374e 100644
--- a/lib/parallel_tests/cucumber/scenarios.rb
+++ b/lib/parallel_tests/cucumber/scenarios.rb
@@ -53,7 +53,7 @@ def split_into_scenarios(files, tags = '')
 
             # We loop on each children of the feature
             test_models = feature.tests
-            test_models += feature.rules.map(&:tests).flatten if feature.respond_to?(:rules)
+            test_models += feature.rules.flat_map(&:tests) if feature.respond_to?(:rules) # cuke_modeler >= 3.2 supports rules
             test_models.each do |test|
               # It's a scenario, we add it to the scenario_line_logger
               scenario_line_logger.visit_feature_element(document.path, test, feature_tags, line_numbers: test_lines)
diff --git a/lib/parallel_tests/test/runner.rb b/lib/parallel_tests/test/runner.rb
index 46e8b62d..317dcac2 100644
--- a/lib/parallel_tests/test/runner.rb
+++ b/lib/parallel_tests/test/runner.rb
@@ -153,8 +153,8 @@ def command_with_seed(cmd, seed)
         protected
 
         def executable
-          if ENV.include?('PARALLEL_TESTS_EXECUTABLE')
-            [ENV.fetch('PARALLEL_TESTS_EXECUTABLE')]
+          if (executable = ENV['PARALLEL_TESTS_EXECUTABLE'])
+            [executable]
           else
             determine_executable
           end
diff --git a/parallel_tests.gemspec b/parallel_tests.gemspec
index 45093e0b..b6d5f3f9 100644
--- a/parallel_tests.gemspec
+++ b/parallel_tests.gemspec
@@ -17,12 +17,5 @@ Gem::Specification.new name, ParallelTests::VERSION do |s|
   s.license = "MIT"
   s.executables = ["parallel_spinach", "parallel_cucumber", "parallel_rspec", "parallel_test"]
   s.add_runtime_dependency "parallel"
-
-  s.add_development_dependency 'cucumber', '~> 4.0'
-  s.add_development_dependency 'cuke_modeler', '~> 3.0'
-  s.add_development_dependency "rake"
-  s.add_development_dependency 'rspec', '~> 3.3'
-  s.add_development_dependency "rubocop"
-
   s.required_ruby_version = '>= 2.5.0'
 end
diff --git a/spec/fixtures/rails70/bin/bundle b/spec/fixtures/rails70/bin/bundle
index 650643e3..25dfd64d 100755
--- a/spec/fixtures/rails70/bin/bundle
+++ b/spec/fixtures/rails70/bin/bundle
@@ -18,7 +18,7 @@ m = Module.new do
   end
 
   def env_var_version
-    ENV.fetch("BUNDLER_VERSION", nil)
+    ENV["BUNDLER_VERSION"]
   end
 
   def cli_arg_version
@@ -38,7 +38,7 @@ m = Module.new do
   end
 
   def gemfile
-    gemfile = ENV.fetch("BUNDLE_GEMFILE", nil)
+    gemfile = ENV["BUNDLE_GEMFILE"]
     return gemfile if gemfile && !gemfile.empty?
 
     File.expand_path('../Gemfile', __dir__)
diff --git a/spec/parallel_tests/cucumber/scenarios_spec.rb b/spec/parallel_tests/cucumber/scenarios_spec.rb
index 88bd42a4..b48b2059 100644
--- a/spec/parallel_tests/cucumber/scenarios_spec.rb
+++ b/spec/parallel_tests/cucumber/scenarios_spec.rb
@@ -233,12 +233,7 @@
     end
   end
 
-  cuke_modeler_version = Gem.loaded_specs['cuke_modeler'].version.version
-  major = cuke_modeler_version.match(/^(\d+)\./)[1].to_i
-  minor = cuke_modeler_version.match(/^\d+\.(\d+)\./)[1].to_i
-
-  # CukeModeler doesn't support Rule models until 3.2.0
-  context 'with Rules', if: (major > 3) || (minor >= 2) do
+  context 'with Rules' do # cuke_modeler >=3.2
     let(:feature_file) do
       Tempfile.new('grouper.feature').tap do |feature|
         feature.write <<-EOS