diff --git a/app/assets/javascripts/discourse/models/composer.js b/app/assets/javascripts/discourse/models/composer.js
index fb3f89845..d7092eaa8 100644
--- a/app/assets/javascripts/discourse/models/composer.js
+++ b/app/assets/javascripts/discourse/models/composer.js
@@ -68,6 +68,10 @@ Discourse.Composer = Discourse.Model.extend({
     return false;
   }.property('editingPost', 'creatingTopic', 'post.post_number'),
 
+  canCategorize: function() {
+    return (this.get('editTitle') && !this.get('creatingPrivateMessage'));
+  }.property('editTitle', 'creatingPrivateMessage'),
+
   showAdminOptions: function() {
     if (this.get('creatingTopic') && Discourse.User.current('staff')) return true;
     return false;
@@ -164,9 +168,8 @@ Discourse.Composer = Discourse.Model.extend({
     //    - creating a new topic
     //    - editing the 1st post
     //    - creating a private message
-    if (this.get('editTitle') &&
-          (this.get('titleLength') < Discourse.SiteSettings.min_topic_title_length ||
-            this.get('titleLength') > Discourse.SiteSettings.max_topic_title_length) ) return true;
+
+    if (this.get('editTitle') && !this.get('titleLengthValid')) return true;
 
     // Need at least one user when sending a private message
     if ( this.get('creatingPrivateMessage') &&
@@ -178,11 +181,20 @@ Discourse.Composer = Discourse.Model.extend({
     // reply is always required
     if (this.get('replyLength') < Discourse.SiteSettings.min_post_length) return true;
 
-    if (this.get('editTitle') && !Discourse.SiteSettings.allow_uncategorized_topics && !this.get('categoryName')) return true;
+    if (this.get('canCategorize') && !Discourse.SiteSettings.allow_uncategorized_topics && !this.get('categoryName')) return true;
 
     return false;
   }.property('loading', 'editTitle', 'titleLength', 'targetUsernames', 'replyLength', 'categoryName'),
 
+  titleLengthValid: function() {
+    if (this.get('creatingPrivateMessage')) {
+      if (this.get('titleLength') < Discourse.SiteSettings.min_private_message_title_length) return false;
+    } else {
+      if (this.get('titleLength') < Discourse.SiteSettings.min_topic_title_length) return false;
+    }
+    return (this.get('titleLength') <= Discourse.SiteSettings.max_topic_title_length);
+  }.property('titleLength'),
+
   // The text for the save button
   saveText: function() {
     switch (this.get('action')) {
@@ -519,7 +531,11 @@ Discourse.Composer = Discourse.Model.extend({
     @property missingTitleCharacters
   **/
   missingTitleCharacters: function() {
-    return Discourse.SiteSettings.min_topic_title_length - this.get('titleLength');
+    if (this.get('creatingPrivateMessage')) {
+      return Discourse.SiteSettings.min_private_message_title_length - this.get('titleLength');
+    } else {
+      return Discourse.SiteSettings.min_topic_title_length - this.get('titleLength');
+    }
   }.property('titleLength'),
 
 
diff --git a/app/assets/javascripts/discourse/views/composer_view.js b/app/assets/javascripts/discourse/views/composer_view.js
index 0db672481..35d1994e5 100644
--- a/app/assets/javascripts/discourse/views/composer_view.js
+++ b/app/assets/javascripts/discourse/views/composer_view.js
@@ -373,10 +373,11 @@ Discourse.ComposerView = Discourse.View.extend({
 
   titleValidation: function() {
     var title = this.get('content.title'), reason;
+    var minLength = (this.get('content.creatingPrivateMessage') ? Discourse.SiteSettings.min_private_message_title_length : Discourse.SiteSettings.min_topic_title_length);
     if( !title || title.length < 1 ){
       reason = Em.String.i18n('composer.error.title_missing');
-    } else if( title.length < Discourse.SiteSettings.min_topic_title_length ) {
-      reason = Em.String.i18n('composer.error.title_too_short', {min: Discourse.SiteSettings.min_topic_title_length})
+    } else if( title.length < minLength ) {
+      reason = Em.String.i18n('composer.error.title_too_short', {min: minLength})
     } else if( title.length > Discourse.SiteSettings.max_topic_title_length ) {
       reason = Em.String.i18n('composer.error.title_too_long', {max: Discourse.SiteSettings.max_topic_title_length})
     }
diff --git a/app/models/site_setting.rb b/app/models/site_setting.rb
index c47782f04..829993e38 100644
--- a/app/models/site_setting.rb
+++ b/app/models/site_setting.rb
@@ -34,6 +34,7 @@ class SiteSetting < ActiveRecord::Base
   client_setting(:max_post_length, 16000)
   client_setting(:min_topic_title_length, 15)
   client_setting(:max_topic_title_length, 255)
+  client_setting(:min_private_message_title_length, 2)
   client_setting(:allow_uncategorized_topics, true)
   client_setting(:min_search_term_length, 3)
   client_setting(:flush_timings_secs, 5)
@@ -227,6 +228,10 @@ class SiteSetting < ActiveRecord::Base
     min_topic_title_length..max_topic_title_length
   end
 
+  def self.private_message_title_length
+    min_private_message_title_length..max_topic_title_length
+  end
+
   def self.post_length
     min_post_length..max_post_length
   end
diff --git a/app/models/topic.rb b/app/models/topic.rb
index 80b3a30d4..139b2850a 100644
--- a/app/models/topic.rb
+++ b/app/models/topic.rb
@@ -39,8 +39,7 @@ class Topic < ActiveRecord::Base
   before_validation :sanitize_title
 
   validates :title, :presence => true,
-                    :length => {  :in => SiteSetting.topic_title_length,
-                                  :allow_blank => true },
+                    :topic_title_length => true,
                     :quality_title => { :unless => :private_message? },
                     :unique_among  => { :unless => Proc.new { |t| (SiteSetting.allow_duplicate_topic_titles? || t.private_message?) },
                                         :message => :has_already_been_used,
diff --git a/config/locales/server.en.yml b/config/locales/server.en.yml
index 8cd7aa048..eed9b0cee 100644
--- a/config/locales/server.en.yml
+++ b/config/locales/server.en.yml
@@ -418,6 +418,7 @@ en:
     max_post_length: "Maximum post length in characters"
     min_topic_title_length: "Minimum topic title length in characters"
     max_topic_title_length: "Maximum topic title length in characters"
+    min_private_message_title_length: "Minimum title length for a private message in characters"
     min_search_term_length: "Minimum search term length in characters"
     allow_uncategorized_topics: "Allow topics to be created without a category"
     allow_duplicate_topic_titles: "Allow topics with identical titles"
diff --git a/lib/validators/topic_title_length_validator.rb b/lib/validators/topic_title_length_validator.rb
new file mode 100644
index 000000000..73783e831
--- /dev/null
+++ b/lib/validators/topic_title_length_validator.rb
@@ -0,0 +1,16 @@
+class TopicTitleLengthValidator < ActiveModel::EachValidator
+
+  def initialize(options)
+    @topic_title_validator = ActiveModel::Validations::LengthValidator.new({attributes: :title, in: SiteSetting.topic_title_length, allow_blank: true})
+    @private_message_title_validator = ActiveModel::Validations::LengthValidator.new({attributes: :title, in: SiteSetting.private_message_title_length, allow_blank: true})
+    super
+  end
+
+  def validate_each(record, attribute, value)
+    if record.private_message?
+      @private_message_title_validator.validate_each(record, attribute, value)
+    else
+      @topic_title_validator.validate_each(record, attribute, value)
+    end
+  end
+end
diff --git a/spec/components/validators/topic_title_length_validator_spec.rb b/spec/components/validators/topic_title_length_validator_spec.rb
new file mode 100644
index 000000000..9b6231624
--- /dev/null
+++ b/spec/components/validators/topic_title_length_validator_spec.rb
@@ -0,0 +1,60 @@
+# encoding: UTF-8
+
+require 'spec_helper'
+require 'validators/topic_title_length_validator'
+
+describe TopicTitleLengthValidator do
+
+  let(:validator) { TopicTitleLengthValidator.new({attributes: :title}) }
+  subject(:validate) { validator.validate_each(record,:title,record.title) }
+
+  shared_examples "validating any topic title" do
+    it 'adds an error when topic title is greater than SiteSetting.max_topic_title_length' do
+      record.title = 'a' * (SiteSetting.max_topic_title_length + 1)
+      validate
+      expect(record.errors[:title]).to be_present
+    end
+  end
+
+  describe 'topic' do
+    let(:record) { Fabricate.build(:topic) }
+
+    it 'adds an error when topic title is shorter than SiteSetting.min_topic_title_length' do
+      record.title = 'a' * (SiteSetting.min_topic_title_length - 1)
+      validate
+      expect(record.errors[:title]).to be_present
+    end
+
+    it 'does not add an error when length is good' do
+      record.title = 'a' * (SiteSetting.min_topic_title_length)
+      validate
+      expect(record.errors[:title]).to_not be_present
+    end
+
+    include_examples "validating any topic title"
+  end
+
+  describe 'private message' do
+    before do
+      SiteSetting.stubs(:min_private_message_title_length).returns(3)
+    end
+
+    let(:record) { Fabricate.build(:private_message_topic) }
+
+    it 'adds an error when topic title is shorter than SiteSetting.min_private_message_title_length' do
+      record.title = 'a' * (SiteSetting.min_private_message_title_length - 1)
+      validate
+      expect(record.errors[:title]).to be_present
+    end
+
+    it 'does not add an error when topic title is shorter than SiteSetting.min_topic_title_length' do
+      SiteSetting.stubs(:min_topic_title_length).returns(15)
+      record.title = 'a' * (SiteSetting.min_private_message_title_length)
+      validate
+      expect(record.errors[:title]).to_not be_present
+    end
+    
+    include_examples "validating any topic title"
+  end
+
+end
diff --git a/spec/models/site_setting_spec.rb b/spec/models/site_setting_spec.rb
index 95d2ca9d8..31584f82b 100644
--- a/spec/models/site_setting_spec.rb
+++ b/spec/models/site_setting_spec.rb
@@ -156,4 +156,11 @@ describe SiteSetting do
       SiteSetting.post_length.should == (SiteSetting.defaults[:min_post_length]..SiteSetting.defaults[:max_post_length])
     end
   end
+
+  describe 'private_message_title_length' do
+    it 'returns a range of min/max pm topic title length' do
+      expect(SiteSetting.private_message_title_length).to eq(SiteSetting.defaults[:min_private_message_title_length]..SiteSetting.defaults[:max_topic_title_length])
+    end
+  end
+
 end
diff --git a/spec/models/topic_spec.rb b/spec/models/topic_spec.rb
index e65ab4cb4..f22d7a98e 100644
--- a/spec/models/topic_spec.rb
+++ b/spec/models/topic_spec.rb
@@ -52,6 +52,23 @@ describe Topic do
     end
   end
 
+  context 'private message title' do
+    before do
+      SiteSetting.stubs(:min_topic_title_length).returns(15)
+      SiteSetting.stubs(:min_private_message_title_length).returns(3)
+    end
+
+    it 'allows shorter titles' do
+      pm = Fabricate.build(:private_message_topic, title: 'a' * SiteSetting.min_private_message_title_length)
+      expect(pm).to be_valid
+    end
+
+    it 'but not too short' do
+      pm = Fabricate.build(:private_message_topic, title: 'a')
+      expect(pm).to_not be_valid
+    end
+  end
+
   context 'topic title uniqueness' do
 
     let!(:topic) { Fabricate(:topic) }