diff --git a/ChangeLog b/ChangeLog
index a31a61218f..dbdaed4b28 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sat Feb 25 17:07:15 2012  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* lib/fileutils.rb: use chomp(?/) instead of sub to optimize and avoid
+	  to regexping invalid string.
+
 Sat Feb 25 16:18:24 2012  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* complex.c (nucomp_marshal_load): raise error on invalid data.
diff --git a/lib/fileutils.rb b/lib/fileutils.rb
index 46dfffb650..6f8add067a 100644
--- a/lib/fileutils.rb
+++ b/lib/fileutils.rb
@@ -281,7 +281,7 @@ public
     fu_output_message "mkdir -p #{options[:mode] ? ('-m %03o ' % options[:mode]) : ''}#{list.join ' '}" if options[:verbose]
     return *list if options[:noop]
 
-    list.map {|path| path.sub(%r</\z>, '') }.each do |path|
+    list.map {|path| path.chomp(?/) }.each do |path|
       # optimize for the most common case
       begin
         fu_mkdir path, options[:mode]
@@ -317,7 +317,7 @@ public
 private
 
   def fu_mkdir(path, mode)   #:nodoc:
-    path = path.sub(%r</\z>, '')
+    path = path.chomp(?/)
     if mode
       Dir.mkdir path, mode
       File.chmod mode, path
@@ -346,7 +346,7 @@ public
     return if options[:noop]
     list.each do |dir|
       begin
-        Dir.rmdir(dir = dir.sub(%r</\z>, ''))
+        Dir.rmdir(dir = dir.chomp(?/))
         if parents
           until (parent = File.dirname(dir)) == '.' or parent == dir
             Dir.rmdir(dir)
@@ -1465,7 +1465,7 @@ private
 
     def remove_dir1
       platform_support {
-        Dir.rmdir path().sub(%r</\z>, '')
+        Dir.rmdir path().chomp(?/)
       }
     end