diff --git a/tests/test_manager.py b/tests/test_manager.py
index 16b63acb0..5dca75bbc 100644
--- a/tests/test_manager.py
+++ b/tests/test_manager.py
@@ -638,7 +638,7 @@ def test_manager_site_import(app, db, superuser):
             }]
     }
     form['site_json'] = Upload(
-        'site_export.json', json.dumps(site_export), 'application/octet-stream')
+        'site_export.json', json.dumps(site_export).encode('ascii'), 'application/octet-stream')
     res = form.submit()
     assert res.status_code == 302
     assert get_role_model().objects.get(slug='basic')
@@ -663,7 +663,7 @@ def test_manager_site_import_error(app, db, superuser):
             }]
     }
     form['site_json'] = Upload(
-        'site_export.json', json.dumps(site_export), 'application/octet-stream')
+        'site_export.json', json.dumps(site_export).encode('ascii'), 'application/octet-stream')
     res = form.submit()
     assert res.status_code == 200
     assert 'missing Organizational Unit' in res.text