diff --git a/app/controllers/messages_controller.rb b/app/controllers/messages_controller.rb
index bbc6a35d4..9bef7a2aa 100644
--- a/app/controllers/messages_controller.rb
+++ b/app/controllers/messages_controller.rb
@@ -50,8 +50,12 @@ class MessagesController < ApplicationController
       offset(@reply_pages.offset).
       to_a
 
-    @reply = Message.new(:subject => "RE: #{@message.subject}")
-    render :action => "show", :layout => false if request.xhr?
+    @reply = Message.new(:subject => "RE: #{@message.subject}") unless @reply
+    if request.xhr?
+      render :action => "show", :layout => false
+    else
+      render :action => "show"
+    end
   end
 
   # Create a new topic
@@ -82,9 +86,11 @@ class MessagesController < ApplicationController
       call_hook(:controller_messages_reply_after_save, { :params => params, :message => @reply})
       attachments = Attachment.attach_files(@reply, params[:attachments])
       render_attachment_warning_if_needed(@reply)
+      flash[:notice] = l(:notice_successful_update)
+      redirect_to board_message_path(@board, @topic, :r => @reply)
+    else
+      show
     end
-    flash[:notice] = l(:notice_successful_update)
-    redirect_to board_message_path(@board, @topic, :r => @reply)
   end
 
   # Edit a message
diff --git a/app/views/messages/show.html.erb b/app/views/messages/show.html.erb
index b8abf0321..cbb5cb112 100644
--- a/app/views/messages/show.html.erb
+++ b/app/views/messages/show.html.erb
@@ -23,6 +23,7 @@
 </div>
 
 <h2><%= avatar(@topic.author) %><%= @topic.subject %></h2>
+<%= error_messages_for 'reply' %>
 
 <div class="message">
 <p><span class="author"><%= authoring @topic.created_on, @topic.author %></span></p>
@@ -81,7 +82,7 @@
 
 <% if !@topic.locked? && authorize_for('messages', 'reply') %>
 <p><%= toggle_link l(:button_reply), "reply", :focus => 'message_content' %></p>
-<div id="reply" style="display:none;">
+<div id="reply" style="<%= 'display:none;' if @reply.errors.blank? %>">
 <%= form_for @reply, :as => :reply, :url => {:action => 'reply', :id => @topic}, :html => {:multipart => true, :id => 'message-form'} do |f| %>
   <%= render :partial => 'form', :locals => {:f => f, :replying => true} %>
   <%= submit_tag l(:button_submit) %>
diff --git a/test/functional/messages_controller_test.rb b/test/functional/messages_controller_test.rb
index ad193b119..9f14a0e19 100644
--- a/test/functional/messages_controller_test.rb
+++ b/test/functional/messages_controller_test.rb
@@ -217,18 +217,39 @@ class MessagesControllerTest < Redmine::ControllerTest
 
   def test_reply
     @request.session[:user_id] = 2
-    post :reply, :params => {
+    assert_difference 'Message.count' do
+      post :reply, :params => {
+          :board_id => 1,
+          :id => 1,
+          :reply => {
+            :content => 'This is a test reply',
+            :subject => 'Test reply'
+          }
+        }
+    end
+    reply = Message.order('id DESC').first
+    assert_redirected_to "/boards/1/topics/1?r=#{reply.id}"
+    assert_equal I18n.t(:notice_successful_update), flash[:notice]
+    assert Message.find_by_subject('Test reply')
+  end
+
+  def test_reply_with_invalid_value_should_show_error_message
+    @request.session[:user_id] = 2
+    assert_no_difference 'Message.count' do
+      post :reply, :params => {
         :board_id => 1,
         :id => 1,
         :reply => {
-          :content => 'This is a test reply',
+          :content => '',
           :subject => 'Test reply'
         }
       }
-    reply = Message.order('id DESC').first
-    assert_redirected_to "/boards/1/topics/1?r=#{reply.id}"
-    assert_equal I18n.t(:notice_successful_update), flash[:notice]
-    assert Message.find_by_subject('Test reply')
+    end
+    assert_select_error 'Content cannot be blank'
+    assert_select 'div#reply' do
+      assert_select 'input#message_subject[value=?]', 'Test reply'
+      assert_select 'textarea#message_content', :text => ''
+    end
   end
 
   def test_destroy_topic