diff --git a/ChangeLog b/ChangeLog
index 27655a1ec1..9b0668caac 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Mon Feb  6 21:55:13 2012  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* tool/merger.rb: abort if the working directory is dirty.
+
+	* tool/merger.rb: update the working directory after commit.
+
 Mon Feb  6 00:16:27 2012  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* encoding.c (rb_enc_compatible): return ASCII-8BIT even if 2nd string
diff --git a/tool/merger.rb b/tool/merger.rb
index 2f9625ce90..673f7b1876 100755
--- a/tool/merger.rb
+++ b/tool/merger.rb
@@ -125,6 +125,11 @@ when nil, "-h", "--help"
   help
   exit
 else
+  unless `svn st`.empty?
+    puts 'this working directory is not clean'
+    abort
+  end
+
   q = $repos + (ARGV[1] || default_merge_branch)
   revs = ARGV[0].split /,\s*/
   log = ''
@@ -199,6 +204,7 @@ else
 
   if system *%w'svn ci -F' + [f.path]
     # tag :interactive # no longer needed.
+    system 'svn up'
     system 'rm -f subversion.commitlog'
   else
     puts 'commit failed; try again.'