diff --git a/Appraisals b/Appraisals
index f0495db..2ccb781 100644
--- a/Appraisals
+++ b/Appraisals
@@ -4,6 +4,10 @@ end
 
 appraise "rack_1_6" do
   gem "rack", "~> 1.6.9"
+
+  # Override rack-test version constraint by making it more loose
+  # so it's compatible with actionpack 4.2.x
+  gem "rack-test", ">= 0.6"
 end
 
 appraise 'rails_5-2' do
@@ -19,6 +23,10 @@ end
 appraise 'rails_4-2' do
   gem 'actionpack', '~> 4.2.0'
   gem 'activesupport', '~> 4.2.0'
+
+  # Override rack-test version constraint by making it more loose
+  # so it's compatible with actionpack 4.2.x
+  gem "rack-test", ">= 0.6"
 end
 
 appraise 'dalli2' do
diff --git a/Guardfile b/Guardfile
deleted file mode 100644
index 06b986b..0000000
--- a/Guardfile
+++ /dev/null
@@ -1,9 +0,0 @@
-# A sample Guardfile
-# More info at https://github.com/guard/guard#readme
-
-guard :minitest do
-  # with Minitest::Spec
-  watch(%r{^spec/(.*)_spec\.rb$})
-  watch(%r{^lib/(.+)\.rb$})         { |m| "spec/#{m[1]}_spec.rb" }
-  watch(%r{^spec/spec_helper\.rb$}) { 'spec' }
-end
diff --git a/gemfiles/rack_1_6.gemfile b/gemfiles/rack_1_6.gemfile
index 18b3acf..8b636ed 100644
--- a/gemfiles/rack_1_6.gemfile
+++ b/gemfiles/rack_1_6.gemfile
@@ -3,5 +3,6 @@
 source "https://rubygems.org"
 
 gem "rack", "~> 1.6.9"
+gem "rack-test", ">= 0.6"
 
 gemspec path: "../"
diff --git a/gemfiles/rails_4_2.gemfile b/gemfiles/rails_4_2.gemfile
index 3937ece..eb09083 100644
--- a/gemfiles/rails_4_2.gemfile
+++ b/gemfiles/rails_4_2.gemfile
@@ -4,5 +4,6 @@ source "https://rubygems.org"
 
 gem "actionpack", "~> 4.2.0"
 gem "activesupport", "~> 4.2.0"
+gem "rack-test", ">= 0.6"
 
 gemspec path: "../"
diff --git a/rack-attack.gemspec b/rack-attack.gemspec
index 9a42e4c..16bbd50 100644
--- a/rack-attack.gemspec
+++ b/rack-attack.gemspec
@@ -31,30 +31,25 @@ Gem::Specification.new do |s|
 
   s.add_dependency 'rack'
 
-  s.add_development_dependency 'actionpack', '>= 3.0.0'
-  s.add_development_dependency 'activesupport', '>= 3.0.0'
-  s.add_development_dependency 'appraisal'
-  s.add_development_dependency 'connection_pool'
-  s.add_development_dependency 'dalli'
-  s.add_development_dependency 'guard-minitest'
-  s.add_development_dependency 'memcache-client'
-  s.add_development_dependency 'minitest'
-  s.add_development_dependency "minitest-stub-const"
-  s.add_development_dependency 'pry'
-  s.add_development_dependency 'rack-test'
-  s.add_development_dependency 'rake'
-  s.add_development_dependency 'redis-activesupport'
+  s.add_development_dependency 'appraisal', '~> 2.2'
+  s.add_development_dependency 'minitest', "~> 5.11"
+  s.add_development_dependency "minitest-stub-const", "~> 0.6"
+  s.add_development_dependency 'rack-test', "~> 1.0"
+  s.add_development_dependency 'rake', "~> 12.3"
   s.add_development_dependency "rubocop", "0.57.2"
-  s.add_development_dependency "timecop"
-
-  # Need to explicitly depend on guard because guard-minitest doesn't declare
-  # the dependency intentionally
-  #
-  # See https://github.com/guard/guard-minitest/pull/131
-  s.add_development_dependency 'guard'
+  s.add_development_dependency "timecop", "~> 0.9.1"
 
   # byebug only works with MRI
   if RUBY_ENGINE == "ruby"
-    s.add_development_dependency 'byebug'
+    s.add_development_dependency 'byebug', '~> 10.0'
   end
+
+  # The following are potential runtime dependencies users may have,
+  # which rack-attack uses only for testing compatibility in test suite.
+  s.add_development_dependency 'actionpack', '>= 3.0.0'
+  s.add_development_dependency 'activesupport', '>= 3.0.0'
+  s.add_development_dependency 'connection_pool'
+  s.add_development_dependency 'dalli'
+  s.add_development_dependency 'memcache-client'
+  s.add_development_dependency 'redis-activesupport'
 end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 6b6f661..7d2c851 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -9,12 +9,6 @@ require 'action_dispatch'
 
 require "rack/attack"
 
-begin
-  require 'pry'
-rescue LoadError
-  # nothing to do here
-end
-
 if RUBY_ENGINE == "ruby"
   require "byebug"
 end