diff --git a/app/controllers/articles_controller.rb b/app/controllers/articles_controller.rb
index c9dd1362..3c3de22a 100644
--- a/app/controllers/articles_controller.rb
+++ b/app/controllers/articles_controller.rb
@@ -227,6 +227,7 @@ class ArticlesController < ApplicationController
     if @updated_articles.empty? && @outlisted_articles.empty?
       redirect_to supplier_articles_path(@supplier), :notice => I18n.t('articles.controller.sync.notice')
     end
+    @ignored_article_count = @supplier.articles.where(order_number: [nil, '']).count
   end
 
   # Updates, deletes articles when sync form is submitted
diff --git a/app/models/article.rb b/app/models/article.rb
index 82fc0b1f..3132f5d0 100644
--- a/app/models/article.rb
+++ b/app/models/article.rb
@@ -61,7 +61,7 @@ class Article < ActiveRecord::Base
   # false will returned and self.shared_updated_on will be updated
   def shared_article_changed?
     # skip early if the timestamp hasn't changed
-    unless self.shared_updated_on == self.shared_article.updated_on
+    unless self.shared_article.nil? or self.shared_updated_on == self.shared_article.updated_on
       
       # try to convert units
       # convert supplier's price and unit_quantity into fc-size
@@ -106,6 +106,7 @@ class Article < ActiveRecord::Base
   
   # to get the correspondent shared article
   def shared_article
+    self.order_number.blank? and return nil
     @shared_article ||= self.supplier.shared_supplier.shared_articles.find_by_number(self.order_number) rescue nil
   end
   
diff --git a/app/models/supplier.rb b/app/models/supplier.rb
index 0dba2a1e..838c9607 100644
--- a/app/models/supplier.rb
+++ b/app/models/supplier.rb
@@ -57,7 +57,9 @@ class Supplier < ActiveRecord::Base
           }
           updated_articles << [article, unequal_attributes]
         end
-      else
+      # Articles with no order number can be used to put non-shared articles
+      # in a shared supplier, with sync keeping them.
+      elsif not article.order_number.blank?
         # article isn't in external database anymore
         outlisted_articles << article
       end
diff --git a/app/views/articles/sync.html.haml b/app/views/articles/sync.html.haml
index 7a990413..a65878f1 100644
--- a/app/views/articles/sync.html.haml
+++ b/app/views/articles/sync.html.haml
@@ -14,6 +14,8 @@
             .alert= t '.outlist.alert_used', article: article.name
   - else
     %i= t '.outlist.body_skip'
+  - if @ignored_article_count > 0
+    %i= t '.outlist.body_ignored', count: @ignored_article_count
   %hr/
   %h2= t '.update.title'
   %p
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 54a409a9..7403cbaf 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -377,6 +377,9 @@ en:
       outlist:
         alert_used: Warning, %{article} is used in an open order. Please remove it from the order first.
         body: ! 'The following articles were removed from the list and will be <b>deleted</b>:'
+        body_ignored:
+          one: One article without order number was skipped.
+          other: ! '%{count} articles without order number were skipped.'
         body_skip: No articles to delete.
         title: Remove from list ...
       price_short: Price
diff --git a/spec/models/article_spec.rb b/spec/models/article_spec.rb
index bd0d991c..0f63b88e 100644
--- a/spec/models/article_spec.rb
+++ b/spec/models/article_spec.rb
@@ -105,5 +105,10 @@ describe Article do
       expect(article.unit_quantity).to eq 5
       expect(article.price).to be_within(1e-3).of(shared_article.price/5)
     end
+
+    it 'does not synchronise when it has no order number' do
+      article.update_attributes :order_number => nil
+      expect(supplier.sync_all).to eq [[], []]
+    end
   end
 end