`bundle install` fails on macOS

[mushitoriami]

When running bundle install by following the instructions in README.asc, I encountered the following error:

% bundle install
Fetching gem metadata from https://rubygems.org/...........
Resolving dependencies...
(omitted)
Installing kindlegen 3.1.1 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    current directory: /Users/sakuramochi/.gem/ruby/3.4.8/gems/kindlegen-3.1.1/ext
/Users/sakuramochi/.rubies/ruby-3.4.8/bin/ruby -rrubygems /Users/sakuramochi/.gem/ruby/3.4.8/gems/rake-13.3.1/exe/rake RUBYARCHDIR\=/Users/sakuramochi/.gem/ruby/3.4.8/extensions/x86_64-darwin-24/3.4.0-static/kindlegen-3.1.1
RUBYLIBDIR\=/Users/sakuramochi/.gem/ruby/3.4.8/extensions/x86_64-darwin-24/3.4.0-static/kindlegen-3.1.1
rake aborted!
Zlib::GzipFile::Error: not in gzip format (Zlib::GzipFile::Error)
/Users/sakuramochi/.gem/ruby/3.4.8/gems/kindlegen-3.1.1/ext/Rakefile:31:in 'Zlib::GzipReader#initialize'
/Users/sakuramochi/.gem/ruby/3.4.8/gems/kindlegen-3.1.1/ext/Rakefile:31:in 'Zlib::GzipReader.open'
/Users/sakuramochi/.gem/ruby/3.4.8/gems/kindlegen-3.1.1/ext/Rakefile:31:in 'block in Object#create_task_for_unix'
/Users/sakuramochi/.gem/ruby/3.4.8/gems/rake-13.3.1/exe/rake:27:in '<main>'
Tasks: TOP => default => install => kindlegen
(See full trace by running task with --trace)
open(https://web.archive.org/web/20200814013519/https://kindlegen.s3.amazonaws.com/KindleGen_Mac_i386_v2_9.zip)
save to KindleGen_Mac_i386_v2_9.zip

rake failed, exit code 1

Gem files will remain installed in /Users/sakuramochi/.gem/ruby/3.4.8/gems/kindlegen-3.1.1 for inspection.
Results logged to /Users/sakuramochi/.gem/ruby/3.4.8/extensions/x86_64-darwin-24/3.4.0-static/kindlegen-3.1.1/gem_make.out

  /Users/sakuramochi/.rubies/ruby-3.4.8/lib/ruby/site_ruby/3.4.0/rubygems/ext/builder.rb:139:in 'Gem::Ext::Builder.run'
  /Users/sakuramochi/.rubies/ruby-3.4.8/lib/ruby/site_ruby/3.4.0/rubygems/ext/rake_builder.rb:33:in 'Gem::Ext::RakeBuilder.build'
  /Users/sakuramochi/.rubies/ruby-3.4.8/lib/ruby/site_ruby/3.4.0/rubygems/ext/builder.rb:218:in 'Gem::Ext::Builder#build_extension'
  /Users/sakuramochi/.rubies/ruby-3.4.8/lib/ruby/site_ruby/3.4.0/rubygems/ext/builder.rb:250:in 'block in Gem::Ext::Builder#build_extensions'
  /Users/sakuramochi/.rubies/ruby-3.4.8/lib/ruby/site_ruby/3.4.0/rubygems/ext/builder.rb:249:in 'Array#each'
  /Users/sakuramochi/.rubies/ruby-3.4.8/lib/ruby/site_ruby/3.4.0/rubygems/ext/builder.rb:249:in 'Gem::Ext::Builder#build_extensions'
  /Users/sakuramochi/.rubies/ruby-3.4.8/lib/ruby/site_ruby/3.4.0/rubygems/installer.rb:809:in 'Gem::Installer#build_extensions'
  /Users/sakuramochi/.rubies/ruby-3.4.8/lib/ruby/site_ruby/3.4.0/bundler/rubygems_gem_installer.rb:115:in 'Bundler::RubyGemsGemInstaller#build_extensions'
  /Users/sakuramochi/.rubies/ruby-3.4.8/lib/ruby/site_ruby/3.4.0/bundler/rubygems_gem_installer.rb:30:in 'Bundler::RubyGemsGemInstaller#install'
  /Users/sakuramochi/.rubies/ruby-3.4.8/lib/ruby/site_ruby/3.4.0/bundler/source/rubygems.rb:217:in 'block in Bundler::Source::Rubygems#install'
  /Users/sakuramochi/.rubies/ruby-3.4.8/lib/ruby/site_ruby/3.4.0/rubygems.rb:1052:in 'Gem.time'
  /Users/sakuramochi/.rubies/ruby-3.4.8/lib/ruby/site_ruby/3.4.0/bundler/source/rubygems.rb:216:in 'Bundler::Source::Rubygems#install'
  /Users/sakuramochi/.rubies/ruby-3.4.8/lib/ruby/site_ruby/3.4.0/bundler/installer/gem_installer.rb:54:in 'Bundler::GemInstaller#install'
  /Users/sakuramochi/.rubies/ruby-3.4.8/lib/ruby/site_ruby/3.4.0/bundler/installer/gem_installer.rb:17:in 'Bundler::GemInstaller#install_from_spec'
  /Users/sakuramochi/.rubies/ruby-3.4.8/lib/ruby/site_ruby/3.4.0/bundler/installer/parallel_installer.rb:133:in 'Bundler::ParallelInstaller#do_install'
  /Users/sakuramochi/.rubies/ruby-3.4.8/lib/ruby/site_ruby/3.4.0/bundler/installer/parallel_installer.rb:124:in 'block in Bundler::ParallelInstaller#worker_pool'
  /Users/sakuramochi/.rubies/ruby-3.4.8/lib/ruby/site_ruby/3.4.0/bundler/worker.rb:62:in 'Bundler::Worker#apply_func'
  /Users/sakuramochi/.rubies/ruby-3.4.8/lib/ruby/site_ruby/3.4.0/bundler/worker.rb:57:in 'block in Bundler::Worker#process_queue'
  <internal:kernel>:168:in 'Kernel#loop'
  /Users/sakuramochi/.rubies/ruby-3.4.8/lib/ruby/site_ruby/3.4.0/bundler/worker.rb:54:in 'Bundler::Worker#process_queue'
  /Users/sakuramochi/.rubies/ruby-3.4.8/lib/ruby/site_ruby/3.4.0/bundler/worker.rb:90:in 'block (2 levels) in Bundler::Worker#create_threads'

An error occurred while installing kindlegen (3.1.1), and Bundler cannot continue.

In Gemfile:
  kindlegen

Environment:

% uname -a
Darwin sakuramochi.local 24.6.0 Darwin Kernel Version 24.6.0: Mon Jul 14 11:30:34 PDT 2025; root:xnu-11417.140.69~1/RELEASE_ARM64_T8103 x86_64
% ruby --version
ruby 3.4.8 (2025-12-17 revision 995b59f666) +PRISM [x86_64-darwin24]