diff --git a/pytrustnfe/nfe/__init__.py b/pytrustnfe/nfe/__init__.py
index 0f1757e6..4b8c0e5c 100644
--- a/pytrustnfe/nfe/__init__.py
+++ b/pytrustnfe/nfe/__init__.py
@@ -55,11 +55,15 @@ def _add_required_node(elemTree):
 
     prods = elemTree.findall('ns:NFe/ns:infNFe/ns:det/ns:prod', namespaces=ns)
     for prod in prods:
-        cEan = etree.Element('cEAN')
-        cEANTrib = etree.Element('cEANTrib')
-        prod.insert(1, cEan)
-        vProd = prod.find('ns:vProd', namespaces=ns)
-        prod.insert(prod.index(vProd) + 1, cEANTrib)
+        element = prod.find('ns:cEAN', namespaces=ns)
+        if element is None:
+            cEan = etree.Element('cEAN')
+            prod.insert(1, cEan)
+        element = prod.find('ns:cEANTrib', namespaces=ns)
+        if element is None:
+            cEANTrib = etree.Element('cEANTrib')
+            vProd = prod.find('ns:vProd', namespaces=ns)
+            prod.insert(prod.index(vProd) + 1, cEANTrib)
     return elemTree
 
 
diff --git a/pytrustnfe/nfe/assinatura.py b/pytrustnfe/nfe/assinatura.py
index 7104e9be..d4ef99cd 100644
--- a/pytrustnfe/nfe/assinatura.py
+++ b/pytrustnfe/nfe/assinatura.py
@@ -36,7 +36,8 @@ def assina_xml(self, xml_element, reference):
         element_signed = signed_root.find(".//*[@Id='%s']" % reference)
         signature = signed_root.find(
             ".//{http://www.w3.org/2000/09/xmldsig#}Signature")
-        if element_signed and signature:
+
+        if element_signed is not None and signature is not None:
             parent = element_signed.getparent()
             parent.append(signature)
         return etree.tostring(signed_root)
diff --git a/setup.py b/setup.py
index 96f3de8b..43dcbf52 100644
--- a/setup.py
+++ b/setup.py
@@ -1,7 +1,7 @@
 # coding=utf-8
 from setuptools import setup, find_packages
 
-VERSION = "0.1.18"
+VERSION = "0.1.19"
 
 setup(
     name="PyTrustNFe",