diff --git a/tests/api/test_responses.py b/tests/api/test_responses.py
index de944dfe7..70886b21a 100644
--- a/tests/api/test_responses.py
+++ b/tests/api/test_responses.py
@@ -54,7 +54,7 @@ def test_openapi_json_behind_proxy(simple_app):
     swagger_json = app_client.get('/v1.0/' + simple_app._spec_file.replace('.yaml', '.json'), headers=headers)
     assert swagger_json.status_code == 200
     assert swagger_json.headers.get('Content-Type') == 'application/json'
-    json_ = swagger_json.json
+    json_ = json.loads(swagger_json.data.decode('utf-8'))
 
     if simple_app._spec_file == 'openapi.yaml':
         assert b'url: "/behind/proxy/v1.0/openapi.json"' in swagger_ui.data