diff --git a/app/models/article.rb b/app/models/article.rb
index 80ef567e..097c6cbb 100644
--- a/app/models/article.rb
+++ b/app/models/article.rb
@@ -18,7 +18,8 @@ class Article < ActiveRecord::Base
   validates_presence_of :name, :unit, :price, :tax, :deposit, :unit_quantity, :supplier_id, :article_category
   validates_length_of :name, :in => 4..60
   validates_length_of :unit, :in => 2..15
-  validates_numericality_of :price, :unit_quantity, :greater_than => 0
+  validates_numericality_of :price, :greater_than_or_equal_to => 0
+  validates_numericality_of :unit_quantity, :greater_than => 0
   validates_numericality_of :deposit, :tax
   validates_uniqueness_of :name, :scope => [:supplier_id, :deleted_at, :type]
   
diff --git a/app/models/article_price.rb b/app/models/article_price.rb
index e946fc92..29e8d507 100644
--- a/app/models/article_price.rb
+++ b/app/models/article_price.rb
@@ -4,7 +4,8 @@ class ArticlePrice < ActiveRecord::Base
   has_many :order_articles
 
   validates_presence_of :price, :tax, :deposit, :unit_quantity
-  validates_numericality_of :price, :unit_quantity, :greater_than => 0
+  validates_numericality_of :price, :greater_than_or_equal_to => 0
+  validates_numericality_of :unit_quantity, :greater_than => 0
   validates_numericality_of :deposit, :tax
 
   localize_input_of :price, :tax, :deposit