diff --git a/lib/rubygems/installer.rb b/lib/rubygems/installer.rb
index 31fb120..d59b56d 100644
--- a/lib/rubygems/installer.rb
+++ b/lib/rubygems/installer.rb
@@ -434,8 +434,7 @@ class Gem::Installer
 
   def check_that_user_bin_dir_is_in_path
     user_bin_dir = @bin_dir || Gem.bindir(gem_home)
-    user_bin_dir.gsub!(File::SEPARATOR, File::ALT_SEPARATOR) if File::ALT_SEPARATOR
-    unless ENV['PATH'].split(File::PATH_SEPARATOR).include? user_bin_dir then
+    unless ENV['PATH'].split(File::PATH_SEPARATOR).index{|dir| File.identical?(user_bin_dir, dir) } then
       unless self.class.path_warning then
         alert_warning "You don't have #{user_bin_dir} in your PATH,\n\t  gem executables will not run."
         self.class.path_warning = true