MS Windows 10
Ruby 2.7.8, 3.2.x
yajl_ext.c error: 'rb_cFixnum' undeclared (first use in this function)
Fixed by changing pygments.rb (2.4.0) yajl-ruby (~> 1.4.3) in gemfile.lock and zenpush.gemspec
Then you can gem build zenpush.gemspec and gem install zenpush-0.3.1.gem