diff --git a/ChangeLog b/ChangeLog
index 4ef00b469c..da28a55e3e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Wed Oct 28 15:02:31 2009  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* gem_prelude.rb (Gem.set_home):
+	  force_encoding(Encoding.filesystem_encoding)
+	  [ruby-dev:39546]
+
+	* gem_prelude.rb (Gem.set_paths): ditto.
+
 Wed Oct 28 14:24:45 2009  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* encoding.c (get_filesystem_encoding):
diff --git a/gem_prelude.rb b/gem_prelude.rb
index ca865aabdc..c60c10b911 100644
--- a/gem_prelude.rb
+++ b/gem_prelude.rb
@@ -67,7 +67,7 @@ if defined?(Gem) then
 
     def self.set_home(home)
       home = home.gsub File::ALT_SEPARATOR, File::SEPARATOR if File::ALT_SEPARATOR
-      @gem_home = home
+      @gem_home = home.force_encoding(Encoding.filesystem_encoding)
     end
 
     def self.set_paths(gpaths)
@@ -87,6 +87,7 @@ if defined?(Gem) then
       end
 
       @gem_path.uniq!
+      @gem_path.map!{|x|x.force_encoding(Encoding.filesystem_encoding)}
     end
 
     def self.user_home