diff --git a/scrapy/contrib/loader/__init__.py b/scrapy/contrib/loader/__init__.py
index 445d72d57..a9fc8f011 100644
--- a/scrapy/contrib/loader/__init__.py
+++ b/scrapy/contrib/loader/__init__.py
@@ -29,7 +29,7 @@ class ItemLoader(object):
 
     def add_value(self, field_name, value, *processors, **kw):
         value = self.get_value(value, *processors, **kw)
-        if not value:
+        if value is None:
             return
         if not field_name:
             for k,v in value.iteritems():
@@ -39,7 +39,7 @@ class ItemLoader(object):
 
     def replace_value(self, field_name, value, *processors, **kw):
         value = self.get_value(value, *processors, **kw)
-        if not value:
+        if value is None:
             return
         if not field_name:
             for k,v in value.iteritems():
diff --git a/scrapy/tests/test_contrib_loader.py b/scrapy/tests/test_contrib_loader.py
index 201362140..8a730e543 100644
--- a/scrapy/tests/test_contrib_loader.py
+++ b/scrapy/tests/test_contrib_loader.py
@@ -68,6 +68,11 @@ class ItemLoaderTest(unittest.TestCase):
         il.add_value(None, u'Jim', lambda x: {'name': x})
         self.assertEqual(il.get_collected_values('name'), [u'Marta', u'Pepe', u'Jim'])
 
+    def test_add_zero(self):
+        il = NameItemLoader()
+        il.add_value('name', 0)
+        self.assertEqual(il.get_collected_values('name'), [0])
+
     def test_replace_value(self):
         il = TestItemLoader()
         il.replace_value('name', u'marta')