diff --git a/operating_system.rb b/operating_system.rb
index b81425f..7b3930e 100644
--- a/operating_system.rb
+++ b/operating_system.rb
@@ -2,15 +2,14 @@ module Gem
   class << self
 
     ##
-    # Returns a string representing that part or the directory tree that is
-    # common to all specified directories.
+    # Returns full path of previous but one directory of dir in path
+    # E.g. for '/usr/share/ruby', 'ruby', it returns '/usr'
 
-    def common_path(dirs)
-      paths = dirs.collect {|dir| dir.split(File::SEPARATOR)}
-      uncommon_idx = paths.transpose.each_with_index.find {|dirnames, idx| dirnames.uniq.length > 1}.last
-      paths[0][0 ... uncommon_idx].join(File::SEPARATOR)
+    def previous_but_one_dir_to(path, dir)
+      split_path = path.split(File::SEPARATOR)
+      File.join(split_path.take_while { |one_dir| one_dir !~ /^#{dir}$/ }[0..-2])
     end
-    private :common_path
+    private :previous_but_one_dir_to
 
     ##
     # Default gems locations allowed on FHS system (/usr, /usr/share).
@@ -19,8 +18,8 @@ module Gem
 
     def default_locations
       @default_locations ||= {
-        :system => common_path([ConfigMap[:vendorlibdir], ConfigMap[:vendorarchdir]]),
-        :local => common_path([ConfigMap[:sitelibdir], ConfigMap[:sitearchdir]])
+        :system => previous_but_one_dir_to(ConfigMap[:vendordir], ConfigMap[:RUBY_INSTALL_NAME]),
+        :local => previous_but_one_dir_to(ConfigMap[:sitedir], ConfigMap[:RUBY_INSTALL_NAME])
       }
     end
 
@@ -29,11 +28,12 @@ module Gem
     # platform independent (:gem_dir) and dependent (:ext_dir) files.
 
     def default_dirs
+      @libdir ||= ConfigMap[:sitelibdir] == ConfigMap[:sitearchdir] ? ConfigMap[:datadir] : ConfigMap[:libdir]
       @default_dirs ||= Hash[default_locations.collect do |destination, path|
         [destination, {
           :bin_dir => File.join(path, ConfigMap[:bindir].split(File::SEPARATOR).last),
           :gem_dir => File.join(path, ConfigMap[:datadir].split(File::SEPARATOR).last, 'gems'),
-          :ext_dir => File.join(path, ConfigMap[:libdir].split(File::SEPARATOR).last, 'gems')
+          :ext_dir => File.join(path, @libdir.split(File::SEPARATOR).last, 'gems')
         }]
       end]
     end
@@ -64,7 +64,7 @@ module Gem
 
     def default_ext_dir_for base_dir
       dirs = Gem.default_dirs.detect {|location, paths| paths[:gem_dir] == base_dir}
-      dirs && File.join(dirs.last[:ext_dir], 'exts')
+      dirs && File.join(dirs.last[:ext_dir], RbConfig::CONFIG['RUBY_INSTALL_NAME'])
     end
   end
 end
diff --git a/ruby.spec b/ruby.spec
index 9b67911..699d5b6 100644
--- a/ruby.spec
+++ b/ruby.spec
@@ -453,7 +453,7 @@ cat >> %{buildroot}%{_sysconfdir}/rpm/macros.rubygems << \EOF
 
 # Common gem locations and files.
 %%gem_instdir %%{gem_dir}/gems/%%{gem_name}-%%{version}
-%%gem_extdir %%{_libdir}/gems/exts/%%{gem_name}-%%{version}
+%%gem_extdir %%{_libdir}/gems/%{name}/%%{gem_name}-%%{version}
 %%gem_libdir %%{gem_instdir}/lib
 %%gem_cache %%{gem_dir}/cache/%%{gem_name}-%%{version}.gem
 %%gem_spec %%{gem_dir}/specifications/%%{gem_name}-%%{version}.gemspec
@@ -468,7 +468,7 @@ cp %{SOURCE1} %{buildroot}%{rubygems_dir}/rubygems/defaults
 mv %{buildroot}%{ruby_libdir}/gems/2.0.0 %{buildroot}%{gem_dir}
 
 # Create folders for gem binary extensions.
-mkdir -p %{buildroot}%{gem_extdir}/exts
+mkdir -p %{buildroot}%{gem_extdir}/%{name}
 
 # Move bundled rubygems to %%gem_dir and %%gem_extdir
 # make symlinks for io-console and bigdecimal, which are considered to be part of stdlib by other Gems
@@ -481,25 +481,25 @@ mv %{buildroot}%{ruby_libdir}/rdoc* %{buildroot}%{gem_dir}/gems/rdoc-%{rdoc_vers
 mv %{buildroot}%{gem_dir}/specifications/default/rdoc-%{rdoc_version}.gemspec %{buildroot}%{gem_dir}/specifications
 
 mkdir -p %{buildroot}%{gem_dir}/gems/bigdecimal-%{bigdecimal_version}/lib
-mkdir -p %{buildroot}%{_libdir}/gems/exts/bigdecimal-%{bigdecimal_version}/lib
+mkdir -p %{buildroot}%{_libdir}/gems/%{name}/bigdecimal-%{bigdecimal_version}/lib
 mv %{buildroot}%{ruby_libdir}/bigdecimal %{buildroot}%{gem_dir}/gems/bigdecimal-%{bigdecimal_version}/lib
-mv %{buildroot}%{ruby_libarchdir}/bigdecimal.so %{buildroot}%{_libdir}/gems/exts/bigdecimal-%{bigdecimal_version}/lib
+mv %{buildroot}%{ruby_libarchdir}/bigdecimal.so %{buildroot}%{_libdir}/gems/%{name}/bigdecimal-%{bigdecimal_version}/lib
 mv %{buildroot}%{gem_dir}/specifications/default/bigdecimal-%{bigdecimal_version}.gemspec %{buildroot}%{gem_dir}/specifications
 ln -s %{gem_dir}/gems/bigdecimal-%{bigdecimal_version}/lib/bigdecimal %{buildroot}%{ruby_libdir}/bigdecimal
-ln -s %{_libdir}/gems/exts/bigdecimal-%{bigdecimal_version}/lib/bigdecimal.so %{buildroot}%{ruby_libarchdir}/bigdecimal.so
+ln -s %{_libdir}/gems/%{name}/bigdecimal-%{bigdecimal_version}/lib/bigdecimal.so %{buildroot}%{ruby_libarchdir}/bigdecimal.so
 
 mkdir -p %{buildroot}%{gem_dir}/gems/io-console-%{io_console_version}/lib
-mkdir -p %{buildroot}%{_libdir}/gems/exts/io-console-%{io_console_version}/lib/io
+mkdir -p %{buildroot}%{_libdir}/gems/%{name}/io-console-%{io_console_version}/lib/io
 mv %{buildroot}%{ruby_libdir}/io %{buildroot}%{gem_dir}/gems/io-console-%{io_console_version}/lib
-mv %{buildroot}%{ruby_libarchdir}/io/console.so %{buildroot}%{_libdir}/gems/exts/io-console-%{io_console_version}/lib/io
+mv %{buildroot}%{ruby_libarchdir}/io/console.so %{buildroot}%{_libdir}/gems/%{name}/io-console-%{io_console_version}/lib/io
 mv %{buildroot}%{gem_dir}/specifications/default/io-console-%{io_console_version}.gemspec %{buildroot}%{gem_dir}/specifications
 ln -s %{gem_dir}/gems/io-console-%{io_console_version}/lib/io %{buildroot}%{ruby_libdir}/io
-ln -s %{_libdir}/gems/exts/io-console-%{io_console_version}/lib/io/console.so %{buildroot}%{ruby_libarchdir}/io/console.so
+ln -s %{_libdir}/gems/%{name}/io-console-%{io_console_version}/lib/io/console.so %{buildroot}%{ruby_libarchdir}/io/console.so
 
 mkdir -p %{buildroot}%{gem_dir}/gems/json-%{json_version}/lib
-mkdir -p %{buildroot}%{_libdir}/gems/exts/json-%{json_version}/lib
+mkdir -p %{buildroot}%{_libdir}/gems/%{name}/json-%{json_version}/lib
 mv %{buildroot}%{ruby_libdir}/json* %{buildroot}%{gem_dir}/gems/json-%{json_version}/lib
-mv %{buildroot}%{ruby_libarchdir}/json/ %{buildroot}%{_libdir}/gems/exts/json-%{json_version}/lib/
+mv %{buildroot}%{ruby_libarchdir}/json/ %{buildroot}%{_libdir}/gems/%{name}/json-%{json_version}/lib/
 mv %{buildroot}%{gem_dir}/specifications/default/json-%{json_version}.gemspec %{buildroot}%{gem_dir}/specifications
 
 mkdir -p %{buildroot}%{gem_dir}/gems/minitest-%{minitest_version}/lib
@@ -507,9 +507,9 @@ mv %{buildroot}%{ruby_libdir}/minitest %{buildroot}%{gem_dir}/gems/minitest-%{mi
 mv %{buildroot}%{gem_dir}/specifications/default/minitest-%{minitest_version}.gemspec %{buildroot}%{gem_dir}/specifications
 
 mkdir -p %{buildroot}%{gem_dir}/gems/psych-%{psych_version}/lib
-mkdir -p %{buildroot}%{_libdir}/gems/exts/psych-%{psych_version}/lib
+mkdir -p %{buildroot}%{_libdir}/gems/%{name}/psych-%{psych_version}/lib
 mv %{buildroot}%{ruby_libdir}/psych* %{buildroot}%{gem_dir}/gems/psych-%{psych_version}/lib
-mv %{buildroot}%{ruby_libarchdir}/psych.so %{buildroot}%{_libdir}/gems/exts/psych-%{psych_version}/lib/
+mv %{buildroot}%{ruby_libarchdir}/psych.so %{buildroot}%{_libdir}/gems/%{name}/psych-%{psych_version}/lib/
 mv %{buildroot}%{gem_dir}/specifications/default/psych-%{psych_version}.gemspec %{buildroot}%{gem_dir}/specifications
 
 # Adjust the gemspec files so that the gems will load properly
@@ -537,7 +537,7 @@ sed -i '/^end$/ i\
 # Install a tapset and fix up the path to the library.
 mkdir -p %{buildroot}%{tapset_dir}
 sed -e "s|@LIBRARY_PATH@|%{tapset_libdir}/libruby.so.%{ruby_version}|" \
-   %{SOURCE2} > %{buildroot}%{tapset_dir}/libruby.so.%{ruby_version}.stp
+  %{SOURCE2} > %{buildroot}%{tapset_dir}/libruby.so.%{ruby_version}.stp
 # Escape '*/' in comment.
 sed -r "s|( \*.*\*)\/(.*)|\1\\\/\2|" %{buildroot}%{tapset_dir}/libruby.so.%{ruby_version}.stp
 
@@ -753,10 +753,10 @@ make check TESTS="-v $DISABLE_TESTS"
 %{gem_dir}
 %exclude %{gem_dir}/gems/*
 %{_exec_prefix}/lib*/gems
-%exclude %{_exec_prefix}/lib*/gems/exts/bigdecimal-%{bigdecimal_version}
-%exclude %{_exec_prefix}/lib*/gems/exts/io-console-%{io_console_version}
-%exclude %{_exec_prefix}/lib*/gems/exts/json-%{json_version}
-%exclude %{_exec_prefix}/lib*/gems/exts/psych-%{psych_version}
+%exclude %{_exec_prefix}/lib*/gems/%{name}/bigdecimal-%{bigdecimal_version}
+%exclude %{_exec_prefix}/lib*/gems/%{name}/io-console-%{io_console_version}
+%exclude %{_exec_prefix}/lib*/gems/%{name}/json-%{json_version}
+%exclude %{_exec_prefix}/lib*/gems/%{name}/psych-%{psych_version}
 %exclude %{gem_dir}/gems/rake-%{rake_version}
 %exclude %{gem_dir}/gems/rdoc-%{rdoc_version}
 %exclude %{gem_dir}/specifications/bigdecimal-%{bigdecimal_version}.gemspec
@@ -800,19 +800,19 @@ make check TESTS="-v $DISABLE_TESTS"
 %files -n rubygem-bigdecimal
 %{ruby_libdir}/bigdecimal
 %{ruby_libarchdir}/bigdecimal.so
-%{_libdir}/gems/exts/bigdecimal-%{bigdecimal_version}
+%{_libdir}/gems/%{name}/bigdecimal-%{bigdecimal_version}
 %{gem_dir}/gems/bigdecimal-%{bigdecimal_version}
 %{gem_dir}/specifications/bigdecimal-%{bigdecimal_version}.gemspec
 
 %files -n rubygem-io-console
 %{ruby_libdir}/io
 %{ruby_libarchdir}/io/console.so
-%{_libdir}/gems/exts/io-console-%{io_console_version}
+%{_libdir}/gems/%{name}/io-console-%{io_console_version}
 %{gem_dir}/gems/io-console-%{io_console_version}
 %{gem_dir}/specifications/io-console-%{io_console_version}.gemspec
 
 %files -n rubygem-json
-%{_libdir}/gems/exts/json-%{json_version}
+%{_libdir}/gems/%{name}/json-%{json_version}
 %{gem_dir}/gems/json-%{json_version}
 %{gem_dir}/specifications/json-%{json_version}.gemspec
 
@@ -821,7 +821,7 @@ make check TESTS="-v $DISABLE_TESTS"
 %{gem_dir}/specifications/minitest-%{minitest_version}.gemspec
 
 %files -n rubygem-psych
-%{_libdir}/gems/exts/psych-%{psych_version}
+%{_libdir}/gems/%{name}/psych-%{psych_version}
 %{gem_dir}/gems/psych-%{psych_version}
 %{gem_dir}/specifications/psych-%{psych_version}.gemspec