Spree does not work with the protected_attributes gem installed

Question

I am upgrading my application from rails 3.2 to rails 4. I am following this Railscast #415 Upgrading to Rails 4

When I tried to start my rails server after adding protected_attributes gem in my Gemfile spree is giving me this error and I am not able to start the server.

Gemfile

source 'https://rubygems.org'

# Other gems
gem 'rails', '~> 4.2.7'
#...
gem 'spree', '~> 3.1.0'

# Gems for upgrading to rails 4
gem 'protected_attributes'
gem 'activeresource'
gem 'activerecord-session_store'
gem 'activerecord-deprecated_finders'

Error:

$ rails server

***************************************************************************
[FATAL] Spree does not work with the protected_attributes gem installed!
You MUST remove this gem from your Gemfile. It is incompatible with Spree.
***************************************************************************

Any help will be appreciated.