```ruby
# coding: utf-8
lib = File.expand_path('../lib', __FILE__)
$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
require 'conditional_counter_cache/version'

Gem::Specification.new do |spec|
  spec.name          = "conditional_counter_cache"
  spec.version       = ConditionalCounterCache::VERSION
  spec.authors       = ["Ryo Nakamura"]
  spec.email         = ["r7kamura@gmail.com"]
  spec.summary       = "Allows you to customize condition of counter cache."
  spec.homepage      = "https://github.com/r7kamura/conditional_counter_cache"
  spec.license       = "MIT"

  spec.files         = `git ls-files -z`.split("\x0")
  spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
  spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
  spec.require_paths = ["lib"]

  spec.add_dependency "activerecord"
  spec.add_dependency "activesupport"
  spec.add_development_dependency "bundler", "~> 1.7"
  spec.add_development_dependency "rails"
  spec.add_development_dependency "rake", "~> 10.0"
  spec.add_development_dependency "rspec", "3.0.2"
  spec.add_development_dependency "rspec-rails"
end
```

Fix supported ActiveRecord version as `[4.0.0, 4.2.0)`
user
```ruby
# coding: utf-8
lib = File.expand_path('../lib', __FILE__)
$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
require 'conditional_counter_cache/version'

Gem::Specification.new do |spec|
  spec.name          = "conditional_counter_cache"
  spec.version       = ConditionalCounterCache::VERSION
  spec.authors       = ["Ryo Nakamura"]
  spec.email         = ["r7kamura@gmail.com"]
  spec.summary       = "Allows you to customize condition of counter cache."
  spec.homepage      = "https://github.com/r7kamura/conditional_counter_cache"
  spec.license       = "MIT"

  spec.files         = `git ls-files -z`.split("\x0")
  spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
  spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
  spec.require_paths = ["lib"]

  spec.add_dependency "activerecord", ">= 4.0.0", "< 4.2.0"
  spec.add_dependency "activesupport"
  spec.add_development_dependency "bundler", "~> 1.7"
  spec.add_development_dependency "rails"
  spec.add_development_dependency "rake", "~> 10.0"
  spec.add_development_dependency "rspec", "3.0.2"
  spec.add_development_dependency "rspec-rails"
end
```
assistant