```ruby
# encoding: utf-8

require File.expand_path('../lib/dm-core/version', __FILE__)

Gem::Specification.new do |gem|
  gem.name        = 'dm-core'
  gem.version     = DataMapper::VERSION
  gem.authors     = ['Dan Kubb']
  gem.email       = %w[dan.kubb@gmail.com]
  gem.description = 'DataMapper core library'
  gem.summary     = gem.description
  gem.homepage    = 'https://github.com/datamapper/dm-core'

  gem.require_paths    = %w[lib]
  gem.files            = `git ls-files`.split($/)
  gem.test_files       = `git ls-files -- spec/*`.split($/)
  gem.extra_rdoc_files = %w[LICENSE README.rdoc]

  gem.add_dependency('addressable', '~> 2.3')

  gem.add_development_dependency('rake',  '~> 10.0.3')
  gem.add_development_dependency('rspec', '~> 1.3.2')
end
```

Update addressable gem dependency to specify minimum version
user
```ruby
# encoding: utf-8

require File.expand_path('../lib/dm-core/version', __FILE__)

Gem::Specification.new do |gem|
  gem.name        = 'dm-core'
  gem.version     = DataMapper::VERSION
  gem.authors     = ['Dan Kubb']
  gem.email       = %w[dan.kubb@gmail.com]
  gem.description = 'DataMapper core library'
  gem.summary     = gem.description
  gem.homepage    = 'https://github.com/datamapper/dm-core'

  gem.require_paths    = %w[lib]
  gem.files            = `git ls-files`.split($/)
  gem.test_files       = `git ls-files -- spec/*`.split($/)
  gem.extra_rdoc_files = %w[LICENSE README.rdoc]

  gem.add_dependency('addressable', '~> 2.3', '>= 2.3.5')

  gem.add_development_dependency('rake',  '~> 10.0.3')
  gem.add_development_dependency('rspec', '~> 1.3.2')
end
```
assistant