rails 5.0.0 при установке nio4r: не удалось создать собственное расширение gem

Вот журналы: http://pastebin.com/CAgur9xd

Installing nio4r 1.2.1 with native extensions

Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    C:/RailsInstaller/Ruby2.2.0/bin/ruby.exe -r ./siteconf20160720-8272-c88sgk.rb extconf.rb --with-cflags=-std=c99
checking for unistd.h... *** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
        --with-opt-dir
        --without-opt-dir
        --with-opt-include
        --without-opt-include=${opt-dir}/include
        --with-opt-lib
        --without-opt-lib=${opt-dir}/lib
        --with-make-prog
        --without-make-prog
        --srcdir=.
        --curdir
        --ruby=C:/RailsInstaller/Ruby2.2.0/bin/$(RUBY_BASE_NAME)
C:/RailsInstaller/Ruby2.2.0/lib/ruby/2.2.0/mkmf.rb:456:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
        from C:/RailsInstaller/Ruby2.2.0/lib/ruby/2.2.0/mkmf.rb:587:in `try_cpp'
         from C:/RailsInstaller/Ruby2.2.0/lib/ruby/2.2.0/mkmf.rb:1060:in `block in have_header'
        from C:/RailsInstaller/Ruby2.2.0/lib/ruby/2.2.0/mkmf.rb:911:in `block in checking_for'
        from C:/RailsInstaller/Ruby2.2.0/lib/ruby/2.2.0/mkmf.rb:351:in `block (2 levels) in postpone'
        from C:/RailsInstaller/Ruby2.2.0/lib/ruby/2.2.0/mkmf.rb:321:in `open'
        from C:/RailsInstaller/Ruby2.2.0/lib/ruby/2.2.0/mkmf.rb:351:in `block in postpone'
        from C:/RailsInstaller/Ruby2.2.0/lib/ruby/2.2.0/mkmf.rb:321:in `open'
        from C:/RailsInstaller/Ruby2.2.0/lib/ruby/2.2.0/mkmf.rb:347:in `postpone'
        from C:/RailsInstaller/Ruby2.2.0/lib/ruby/2.2.0/mkmf.rb:910:in `checking_for'
        from C:/RailsInstaller/Ruby2.2.0/lib/ruby/2.2.0/mkmf.rb:1059:in `have_header'
        from extconf.rb:3:in `<main>'

extconf failed, exit code 1

при установке пакета он возвращается (начинается со строки 117 в журналах):

Installing nio4r 1.2.1 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

Таким образом, пакет не может быть установлен. Он возвращается в конце:

An error occurred while installing nio4r (1.2.1), and Bundler cannot continue.
Make sure that `gem install nio4r -v '1.2.1'` succeeds before bundling.

Примечание. Я пробовал решения в других вопросах, но они все те же. Если можно установить "nio4r" вручную, скажите, пожалуйста, как.