diff --git a/mayan/apps/sources/classes.py b/mayan/apps/sources/classes.py
index 34213afa76..ea64144278 100644
--- a/mayan/apps/sources/classes.py
+++ b/mayan/apps/sources/classes.py
@@ -3,7 +3,14 @@ from __future__ import unicode_literals
 import base64
 import os
 import time
-import urllib
+
+try:
+    # Python 2
+    from urllib import unquote_plus
+except ImportError:
+    # Python 3
+    from urllib.parse import unquote_plus
+
 
 from django.core.files import File
 from django.urls import reverse
@@ -39,7 +46,7 @@ class StagingFile(object):
         if encoded_filename:
             self.encoded_filename = str(encoded_filename)
             self.filename = base64.urlsafe_b64decode(
-                urllib.unquote_plus(self.encoded_filename)
+                unquote_plus(self.encoded_filename)
             ).decode('utf8')
         else:
             self.filename = filename
diff --git a/mayan/apps/sources/tests/test_views.py b/mayan/apps/sources/tests/test_views.py
index b7f9712941..2994fc24dc 100644
--- a/mayan/apps/sources/tests/test_views.py
+++ b/mayan/apps/sources/tests/test_views.py
@@ -40,7 +40,7 @@ class DocumentUploadTestCase(GenericDocumentViewTestCase):
         self.document.delete()
 
     def _request_upload_wizard(self):
-        with open(TEST_SMALL_DOCUMENT_PATH) as file_object:
+        with open(TEST_SMALL_DOCUMENT_PATH, 'rb') as file_object:
             return self.post(
                 'sources:upload_interactive', args=(self.source.pk,), data={
                     'source-file': file_object,
@@ -82,7 +82,7 @@ class DocumentUploadTestCase(GenericDocumentViewTestCase):
             obj=self.document_type, permission=permission_document_create
         )
 
-        with open(TEST_SMALL_DOCUMENT_PATH) as file_object:
+        with open(TEST_SMALL_DOCUMENT_PATH, 'rb') as file_object:
             response = self.post(
                 'sources:upload_interactive', args=(self.source.pk,), data={
                     'source-file': file_object,
@@ -142,7 +142,7 @@ class DocumentUploadIssueTestCase(GenericViewTestCase):
         self.assertEqual(WebFormSource.objects.count(), 1)
 
         # Upload the test document
-        with open(TEST_SMALL_DOCUMENT_PATH) as file_descriptor:
+        with open(TEST_SMALL_DOCUMENT_PATH, 'rb') as file_descriptor:
             self.post(
                 'sources:upload_interactive', data={
                     'document-language': 'eng', 'source-file': file_descriptor,