3 files changed, 19 insertions, 8 deletions
diff --git a/lib/rubygems/ext/builder.rb b/lib/rubygems/ext/builder.rb
index 6382a8f5c7..b3b9033962 100644
--- a/lib/rubygems/ext/builder.rb
+++ b/lib/rubygems/ext/builder.rb
@@ -148,9 +148,21 @@ EOF
   def build_extension extension, dest_path # :nodoc:
     results = []
 
+    # FIXME: Determine if this line is necessary and, if so, why.
+    # Notes:
+    # 1. As far as I can tell, this method is only called by +build_extensions+.
+    # 2. The existence of this line implies +extension+ is, or previously was,
+    #    sometimes +false+ or +nil+.
+    # 3. #1 and #2 combined suggests, but does not confirm, that
+    #    +@specs.extensions+ sometimes contained +false+ or +nil+ values.
+    # 4. Nothing seems to explicitly handle +extension+ being empty,
+    #    which makes me wonder both what it should do and what it does.
+    #
+    # - @duckinator
     extension ||= '' # I wish I knew why this line existed
+
     extension_dir =
-      File.expand_path File.join @gem_dir, File.dirname(extension)
+      File.expand_path File.join(@gem_dir, File.dirname(extension))
     lib_dir = File.join @spec.full_gem_path, @spec.raw_require_paths.first
 
     builder = builder_for extension
@@ -200,6 +212,7 @@ EOF
 
     FileUtils.rm_f @spec.gem_build_complete_path
 
+    # FIXME: action at a distance: @ran_rake modified deep in build_extension(). - @duckinator
     @ran_rake = false # only run rake once
 
     @spec.extensions.each do |extension|
diff --git a/lib/rubygems/ext/ext_conf_builder.rb b/lib/rubygems/ext/ext_conf_builder.rb
index a17881a890..18e300d8c2 100644
--- a/lib/rubygems/ext/ext_conf_builder.rb
+++ b/lib/rubygems/ext/ext_conf_builder.rb
@@ -38,7 +38,7 @@ class Gem::Ext::ExtConfBuilder < Gem::Ext::Builder
       destdir = ENV["DESTDIR"]
 
       begin
-        cmd = [Gem.ruby, "-r", get_relative_path(siteconf.path), File.basename(extension), *args].join ' '
+        cmd = [Gem.ruby, "-I", File.expand_path("../../..", __FILE__), "-r", get_relative_path(siteconf.path), File.basename(extension), *args].join ' '
 
         begin
           run cmd, results
diff --git a/lib/rubygems/ext/rake_builder.rb b/lib/rubygems/ext/rake_builder.rb
index 7a5a48c6cc..890803aaef 100644
--- a/lib/rubygems/ext/rake_builder.rb
+++ b/lib/rubygems/ext/rake_builder.rb
@@ -5,6 +5,8 @@
 # See LICENSE.txt for permissions.
 #++
 
+require "shellwords"
+
 class Gem::Ext::RakeBuilder < Gem::Ext::Builder
 
   def self.build(extension, dest_path, results, args=[], lib_dir=nil)
@@ -14,9 +16,6 @@ class Gem::Ext::RakeBuilder < Gem::Ext::Builder
       run cmd, results
     end
 
-    # Deal with possible spaces in the path, e.g. C:/Program Files
-    dest_path = '"' + dest_path.to_s + '"' if dest_path.to_s.include?(' ')
-
     rake = ENV['rake']
 
     rake ||= begin
@@ -26,9 +25,8 @@ class Gem::Ext::RakeBuilder < Gem::Ext::Builder
 
     rake ||= Gem.default_exec_format % 'rake'
 
-    cmd = "#{rake} RUBYARCHDIR=#{dest_path} RUBYLIBDIR=#{dest_path}" # ENV is frozen
-
-    run cmd, results
+    rake_args = ["RUBYARCHDIR=#{dest_path}", "RUBYLIBDIR=#{dest_path}", *args]
+    run "#{rake} #{rake_args.shelljoin}", results
 
     results
   end