diff --git a/__init__.py b/__init__.py
index c67a10c..cd83ba6 100644
--- a/__init__.py
+++ b/__init__.py
@@ -1,12 +1,12 @@
-#This file is part account_invoice_taxes_required module for Tryton.
-#The COPYRIGHT file at the top level of this repository contains
-#the full copyright notices and license terms.
+# This file is part account_invoice_taxes_required module for Tryton.
+# The COPYRIGHT file at the top level of this repository contains
+# the full copyright notices and license terms.
 from trytond.pool import Pool
-from .invoice import *
+from . import invoice
 
 
 def register():
     Pool.register(
-        Invoice,
-        InvoiceLine,
+        invoice.Invoice,
+        invoice.InvoiceLine,
         module='account_invoice_taxes_required', type_='model')
diff --git a/invoice.py b/invoice.py
index 2a4b115..e0d86c5 100644
--- a/invoice.py
+++ b/invoice.py
@@ -1,6 +1,6 @@
-#This file is part account_invoice_taxes_required module for Tryton.
-#The COPYRIGHT file at the top level of this repository contains
-#the full copyright notices and license terms.
+# This file is part account_invoice_taxes_required module for Tryton.
+# The COPYRIGHT file at the top level of this repository contains
+# the full copyright notices and license terms.
 
 from trytond.pool import Pool, PoolMeta
 
diff --git a/tests/__init__.py b/tests/__init__.py
index 08ce081..247add6 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -1,7 +1,6 @@
-#This file is part account_invoice_taxes_required module for Tryton.
-#The COPYRIGHT file at the top level of this repository contains
-#the full copyright notices and license terms.
-from .test_account_invoice_taxes_required import suite
+# This file is part account_invoice_taxes_required module for Tryton.
+# The COPYRIGHT file at the top level of this repository contains
+# the full copyright notices and license terms.
 try:
     from trytond.modules.account_invoice_taxes_required.tests.test_account_invoice_taxes_required import suite
 except ImportError: