diff --git a/helpdesk/tests/test_attachments.py b/helpdesk/tests/test_attachments.py
index b8f16b28..9476facf 100644
--- a/helpdesk/tests/test_attachments.py
+++ b/helpdesk/tests/test_attachments.py
@@ -82,7 +82,7 @@ class AttachmentIntegrationTests(TestCase):
         # Ensure attachment is available with correct content
         att = models.FollowUpAttachment.objects.get(
             followup__ticket=response.context['ticket'])
-        with open(os.path.join(MEDIA_DIR, att.file.name)) as file_on_disk:
+        with open(os.path.join(MEDIA_DIR, att.file.name), encoding="utf-8") as file_on_disk:
             disk_content = smart_str(file_on_disk.read(), 'utf-8')
         self.assertEqual(disk_content, 'โจ')
 
diff --git a/helpdesk/tests/test_get_email.py b/helpdesk/tests/test_get_email.py
index be1860ae..944bbafa 100644
--- a/helpdesk/tests/test_get_email.py
+++ b/helpdesk/tests/test_get_email.py
@@ -56,7 +56,7 @@ class GetEmailCommonTests(TestCase):
         Tests that emails with blank bodies and attachments work.
         https://github.com/django-helpdesk/django-helpdesk/issues/700
         """
-        with open(os.path.join(THIS_DIR, "test_files/blank-body-with-attachment.eml")) as fd:
+        with open(os.path.join(THIS_DIR, "test_files/blank-body-with-attachment.eml"), encoding="utf-8") as fd:
             test_email = fd.read()
             ticket = helpdesk.email.object_from_message(
                 test_email, self.queue_public, self.logger)
@@ -73,7 +73,7 @@ class GetEmailCommonTests(TestCase):
         """
         Tests that emails with quoted-printable bodies work.
         """
-        with open(os.path.join(THIS_DIR, "test_files/quoted_printable.eml")) as fd:
+        with open(os.path.join(THIS_DIR, "test_files/quoted_printable.eml"), encoding="utf-8") as fd:
             test_email = fd.read()
             ticket = helpdesk.email.object_from_message(
                 test_email, self.queue_public, self.logger)
@@ -94,7 +94,7 @@ class GetEmailCommonTests(TestCase):
         Tests that emails with 8bit transfer encoding and utf-8 charset
         https://github.com/django-helpdesk/django-helpdesk/issues/732
         """
-        with open(os.path.join(THIS_DIR, "test_files/all-special-chars.eml")) as fd:
+        with open(os.path.join(THIS_DIR, "test_files/all-special-chars.eml"), encoding="utf-8") as fd:
             test_email = fd.read()
             ticket = helpdesk.email.object_from_message(
                 test_email, self.queue_public, self.logger)
@@ -107,7 +107,7 @@ class GetEmailCommonTests(TestCase):
         Tests that emails with utf-8 non-decodable sequences are parsed correctly
         The message is fowarded as well
         """
-        with open(os.path.join(THIS_DIR, "test_files/utf-nondecodable.eml")) as fd:
+        with open(os.path.join(THIS_DIR, "test_files/utf-nondecodable.eml"), encoding="utf-8") as fd:
             test_email = fd.read()
         ticket = helpdesk.email.object_from_message(
             test_email, self.queue_public, self.logger)
@@ -126,7 +126,7 @@ class GetEmailCommonTests(TestCase):
         """
         Forwarded message of that format must be still attached correctly
         """
-        with open(os.path.join(THIS_DIR, "test_files/forwarded-message.eml")) as fd:
+        with open(os.path.join(THIS_DIR, "test_files/forwarded-message.eml"), encoding="utf-8") as fd:
             test_email = fd.read()
         ticket = helpdesk.email.object_from_message(
             test_email, self.queue_public, self.logger)
@@ -708,7 +708,7 @@ class GetEmailParametricTemplate(object):
            and PGP signatures appropriately."""
 
         # example email text from #567 on GitHub
-        with open(os.path.join(THIS_DIR, "test_files/pgp.eml")) as fd:
+        with open(os.path.join(THIS_DIR, "test_files/pgp.eml"), encoding="utf-8") as fd:
             test_email = fd.read()
         test_mail_len = len(test_email)