diff --git a/pytrustnfe/nfe/__init__.py b/pytrustnfe/nfe/__init__.py
index 6a3d1d5..1433dd4 100644
--- a/pytrustnfe/nfe/__init__.py
+++ b/pytrustnfe/nfe/__init__.py
@@ -134,6 +134,12 @@ def _send(certificado, method, **kwargs):
 
     port = next(iter(client.wsdl.port_types))
     first_operation = next(iter(client.wsdl.port_types[port].operations))
+    
+    if kwargs['estado'] == '41':
+        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)