Railsでのbundle installでjsonのnative extention errorが発生する

Question

###Everyday Rails - RSpecによるRailsテスト入門を学習しようとして…

Githubからcloneしてきて、bundle installしようとした際に以下のようなエラーが発生しました。
json 1.8.1がエラーの原因だと思うのですが...

###発生している問題・エラーメッセージ

Installing json 1.8.1 with native extensions

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

    current directory: /Users/straysheep/rails-4-1-rspec-3-0/vendor/bundle/ruby/2.3.0/gems/json-1.8.1/ext/json/ext/generator
/usr/local/opt/ruby/bin/ruby -r ./siteconf20160725-78651-vk5vc8.rb extconf.rb
creating Makefile

current directory: /Users/straysheep/rails-4-1-rspec-3-0/vendor/bundle/ruby/2.3.0/gems/json-1.8.1/ext/json/ext/generator
make "DESTDIR=" clean

current directory: /Users/straysheep/rails-4-1-rspec-3-0/vendor/bundle/ruby/2.3.0/gems/json-1.8.1/ext/json/ext/generator
make "DESTDIR="
compiling generator.c
In file included from generator.c:1:
./../fbuffer/fbuffer.h:175:47: error: too few arguments provided to function-like macro invocation
    VALUE result = rb_str_new(FBUFFER_PAIR(fb));
                                              ^
/usr/local/Cellar/ruby/2.3.1/include/ruby-2.3.0/ruby/intern.h:797:9: note: macro 'rb_str_new' defined here
#define rb_str_new(str, len) __extension__ (    \
        ^
In file included from generator.c:1:
./../fbuffer/fbuffer.h:175:11: warning: incompatible pointer to integer conversion initializing 'VALUE' (aka 'unsigned long') with an expression of type 'VALUE (const char *, long)' (aka 'unsigned long (const char *, long)') [-Wint-conversion]
    VALUE result = rb_str_new(FBUFFER_PAIR(fb));
          ^        ~~~~~~~~~~
1 warning and 1 error generated.
make: *** [generator.o] Error 1

make failed, exit code 2

Gem files will remain installed in /Users/straysheep/rails-4-1-rspec-3-0/vendor/bundle/ruby/2.3.0/gems/json-1.8.1 for inspection.
Results logged to /Users/straysheep/rails-4-1-rspec-3-0/vendor/bundle/ruby/2.3.0/extensions/x86_64-darwin-15/2.3.0/json-1.8.1/gem_make.out

###試したこと

$ bundle install --path ~/ディレクトリ名/vendor/bundle

上記を実行してみるも、変わらず。
また、json -v 1.8.1 をインストールしてみるもダメでした。

###補足情報 僕の環境のgem list (json)

json (2.0.1, 2.0.0, 1.8.3)
json_pure (2.0.1, 1.8.1)