--- a/tool/rbinstall.rb.~1~	2018-12-27 07:43:59.938638174 +0100
+++ b/tool/rbinstall.rb	2018-12-27 07:51:09.096382161 +0100
@@ -723,17 +723,7 @@
 # :startdoc:
 
 install?(:ext, :arch, :gem, :'default-gems', :'default-gems-arch') do
-  install_default_gem('ext', srcdir) do |path|
-    # assume that gemspec and extconf.rb are placed in the same directory
-    success = false
-    begin
-      IO.foreach(File.dirname(path[(srcdir.size+1)..-1]) + "/Makefile") do |l|
-        break success = true if /^TARGET\s*=/ =~ l
-      end
-    rescue Errno::ENOENT
-    end
-    success
-  end
+  # Gems are unbundled in Gentoo
 end
 
 def load_gemspec(file)
@@ -743,7 +743,7 @@
 end
 
 def install_default_gem(dir, srcdir)
-  gem_dir = Gem.default_dir
+  gem_dir = ENV['GEM_DESTDIR'] ; puts "gem_dir for default gems = #{gem_dir}"
   directories = Gem.ensure_gem_subdirectories(gem_dir, :mode => $dir_mode)
   prepare "default gems from #{dir}", gem_dir, directories
 
@@ -777,7 +777,7 @@
 end
 
 install?(:ext, :comm, :gem, :'bundled-gems') do
-  gem_dir = Gem.default_dir
+  gem_dir = ENV['GEM_DESTDIR']
   directories = Gem.ensure_gem_subdirectories(gem_dir, :mode => $dir_mode)
   prepare "bundled gems", gem_dir, directories
   install_dir = with_destdir(gem_dir)