diff --git a/pytrustnfe/nfe/__init__.py b/pytrustnfe/nfe/__init__.py
index 0f80937..72786b7 100644
--- a/pytrustnfe/nfe/__init__.py
+++ b/pytrustnfe/nfe/__init__.py
@@ -135,6 +135,11 @@ def _send(certificado, method, **kwargs):
     port = next(iter(client.wsdl.port_types))
     first_operation = [x for x in iter(
         client.wsdl.port_types[port].operations) if "Zip" not in x][0]
+
+    namespaceNFe = xml.find(".//{http://www.portalfiscal.inf.br/nfe}NFe")
+    if namespaceNFe is not None:
+        namespaceNFe.set('xmlns', 'http://www.portalfiscal.inf.br/nfe')
+
     with client.settings(raw_response=True):
         response = client.service[first_operation](xml)
         response, obj = sanitize_response(response.text)