diff --git a/pytrustnfe/nfe/assinatura.py b/pytrustnfe/nfe/assinatura.py
index 9520ace..ae496b2 100644
--- a/pytrustnfe/nfe/assinatura.py
+++ b/pytrustnfe/nfe/assinatura.py
@@ -2,6 +2,7 @@
 # © 2016 Danimar Ribeiro, Trustcode
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
 
+from builtins import object
 import signxml
 from lxml import etree
 from pytrustnfe.certificado import extract_cert_and_key_from_pfx
diff --git a/pytrustnfe/nfse/assinatura.py b/pytrustnfe/nfse/assinatura.py
index b2a8d28..4ec4b63 100644
--- a/pytrustnfe/nfse/assinatura.py
+++ b/pytrustnfe/nfse/assinatura.py
@@ -5,6 +5,9 @@
 import xmlsec
 import libxml2
 import os.path
+from builtins import str
+from builtins import range
+from builtins import object
 
 NAMESPACE_SIG = 'http://www.w3.org/2000/09/xmldsig#'
 
diff --git a/pytrustnfe/xml/filters.py b/pytrustnfe/xml/filters.py
index b65d98d..3fee9f0 100644
--- a/pytrustnfe/xml/filters.py
+++ b/pytrustnfe/xml/filters.py
@@ -2,6 +2,9 @@
 # © 2016 Danimar Ribeiro, Trustcode
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
 
+from __future__ import division
+from builtins import str
+from past.utils import old_div
 from decimal import Decimal
 from datetime import date
 from datetime import datetime
@@ -13,8 +16,8 @@ def normalize_str(string):
     Remove special characters and return the ascii string
     """
     if string:
-        if not isinstance(string, unicode):
-            string = unicode(string, 'utf-8', 'replace')
+        if not isinstance(string, str):
+            string = str(string, 'utf-8', 'replace')
 
         string = string.encode('utf-8')
         return normalize(
@@ -24,7 +27,7 @@ def normalize_str(string):
 
 def format_percent(value):
     if value:
-        return Decimal(value) / 100
+        return old_div(Decimal(value), 100)
 
 
 def format_datetime(value):