diff --git a/plugins/shopping_cart/controllers/shopping_cart_plugin_controller.rb b/plugins/shopping_cart/controllers/shopping_cart_plugin_controller.rb
index 8eb1747..e2b8baa 100644
--- a/plugins/shopping_cart/controllers/shopping_cart_plugin_controller.rb
+++ b/plugins/shopping_cart/controllers/shopping_cart_plugin_controller.rb
@@ -94,10 +94,12 @@ class ShoppingCartPluginController < PublicController
   end
 
   def buy
-    @cart = cart
-    @enterprise = environment.enterprises.find(cart[:enterprise_id])
-    @settings = Noosfero::Plugin::Settings.new(@enterprise, ShoppingCartPlugin)
-    render :layout => false
+    if validate_cart_presence
+      @cart = cart
+      @enterprise = environment.enterprises.find(cart[:enterprise_id])
+      @settings = Noosfero::Plugin::Settings.new(@enterprise, ShoppingCartPlugin)
+      render :layout => false
+    end
   end
 
   def send_request
diff --git a/plugins/shopping_cart/test/functional/shopping_cart_plugin_controller_test.rb b/plugins/shopping_cart/test/functional/shopping_cart_plugin_controller_test.rb
index 618ac9f..657ff9c 100644
--- a/plugins/shopping_cart/test/functional/shopping_cart_plugin_controller_test.rb
+++ b/plugins/shopping_cart/test/functional/shopping_cart_plugin_controller_test.rb
@@ -187,6 +187,12 @@ class ShoppingCartPluginControllerTest < ActionController::TestCase
     assert !cart?, "cart expected to be empty!"
   end
 
+  should 'not allow buy without any cart' do
+    get :buy
+    assert !json_response[:ok]
+    assert_equal 2, json_response['error']['code']
+  end
+
   private
 
   def json_response
--
libgit2 0.21.2