diff --git a/ChangeLog b/ChangeLog
index d85932fd36..dba1928bf5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sat Apr  3 04:46:00 2010  Tanaka Akira  <akr@fsij.org>
+
+	* tool/file2lastrev.rb (VCS#relative_to): path and @srcdir may have
+	  different relative-ness.
+
 Sat Apr  3 03:19:01 2010  Kazuhiro NISHIYAMA  <zn@mbf.nifty.com>
 
 	* lib/benchmark.rb (Benchmark::Tms#add): fix NameError.
diff --git a/tool/file2lastrev.rb b/tool/file2lastrev.rb
index 53774d6d34..cf15389112 100755
--- a/tool/file2lastrev.rb
+++ b/tool/file2lastrev.rb
@@ -38,7 +38,22 @@ class VCS
   end
 
   def relative_to(path)
-    path ? Pathname(path).relative_path_from(@srcdir) : '.'
+    if path
+      path = Pathname(path)
+      srcdir = @srcdir
+      if path.absolute? ^ srcdir.absolute?
+        if path.absolute?
+          srcdir = srcdir.expand_path
+        end
+      else
+        if srcdir.absolute?
+          path = path.expand_path
+        end
+      end
+      path.relative_path_from(srcdir)
+    else
+      '.'
+    end
   end
 
   class SVN < self