diff --git a/ChangeLog b/ChangeLog
index 414cc1d5a5..f7f2c36ad2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Thu Jan  1 06:56:28 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* tool/file2lastrev.rb: unset PWD.
+
 Wed Dec 31 23:37:17 2008  Tanaka Akira  <akr@fsij.org>
 
 	* ext/socket/socket.c (sock_s_socketpair): yield if a block is given.
diff --git a/tool/file2lastrev.rb b/tool/file2lastrev.rb
index 01ac1bbced..37b27b2b88 100644
--- a/tool/file2lastrev.rb
+++ b/tool/file2lastrev.rb
@@ -1,5 +1,8 @@
 #!/usr/bin/env ruby
 
+ENV['LANG'] = ENV['LC_ALL'] = ENV['LC_MESSAGES'] = 'C'
+ENV.delete('PWD')
+
 require 'optparse'
 require 'pathname'
 
@@ -14,7 +17,6 @@ def detect_vcs(path)
 end
 
 def get_revisions(path)
-  ENV['LANG'] = ENV['LC_ALL'] = ENV['LC_MESSAGES'] = 'C'
   vcs, path = detect_vcs(path)
 
   info = case vcs