diff --git a/muk_web_preview_attachment/tests/test_attachment_extension.py b/muk_web_preview_attachment/tests/test_attachment_extension.py
index bb98835..45726ec 100644
--- a/muk_web_preview_attachment/tests/test_attachment_extension.py
+++ b/muk_web_preview_attachment/tests/test_attachment_extension.py
@@ -43,7 +43,7 @@ class AttachmentExtensionTestCase(common.TransactionCase):
         super(AttachmentExtensionTestCase, self).tearDown()
         
     def test_attachment_extension_filename(self):
-        with closing(open(os.path.join(_path, 'tests/data/sample.png'), 'r')) as file:
+        with closing(open(os.path.join(_path, 'tests/data/sample.png'), 'rb')) as file:
             self.sample = self.attachment_model.create({
                 'name': "test",
                 'datas_fname': "sample.png",
@@ -52,7 +52,7 @@ class AttachmentExtensionTestCase(common.TransactionCase):
         self.assertEqual(self.sample.extension, ".png")
         
     def test_attachment_extension_mimetype(self):
-        with closing(open(os.path.join(_path, 'tests/data/sample.png'), 'r')) as file:
+        with closing(open(os.path.join(_path, 'tests/data/sample.png'), 'rb')) as file:
             self.sample = self.attachment_model.create({
                 'name': "test",
                 'mimetype': "image/png",
diff --git a/muk_web_preview_mail/tests/test_mail_parse.py b/muk_web_preview_mail/tests/test_mail_parse.py
index 64283ed..0e7f5e6 100644
--- a/muk_web_preview_mail/tests/test_mail_parse.py
+++ b/muk_web_preview_mail/tests/test_mail_parse.py
@@ -40,7 +40,7 @@ class MailParseTestCase(common.TransactionCase):
     def setUp(self):
         super(MailParseTestCase, self).setUp()
         self.attachment_model = self.env['ir.attachment'].sudo()
-        with closing(open(os.path.join(_path, 'tests/data/sample.eml'), 'r')) as file:
+        with closing(open(os.path.join(_path, 'tests/data/sample.eml'), 'rb')) as file:
             self.sample_mail_attachment = self.attachment_model.create({
                 'name': 'SampleMail',
                 'datas_fname': "sample.eml",