diff --git a/tests/test_utils.py b/tests/test_utils.py
index 29dd4b85..bc585287 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -164,7 +164,7 @@ class TestContentEncodingDetection:
         data = (i for i in [b'a', b'b', b'c']) 
 
         with server as (host, port):
-            url = 'http://{}:{}/'.format(host, port)
+            url = 'http://{0}:{1}/'.format(host, port)
             r = requests.post(url, data=data, stream=True)
             block_server.set() # release server block
 
@@ -288,7 +288,7 @@ class TestTestServer:
         )
 
         with server as (host, port):
-            r = requests.get('http://{}:{}'.format(host, port))
+            r = requests.get('http://{0}:{1}'.format(host, port))
 
             assert r.status_code == 200
             assert r.text == 'roflol'
@@ -296,7 +296,7 @@ class TestTestServer:
             
     def test_basic_response(self):
         with Server.basic_response_server() as (host, port):
-            r = requests.get('http://{}:{}'.format(host, port))
+            r = requests.get('http://{0}:{1}'.format(host, port))
             assert r.status_code == 200
             assert r.text == ''
             assert r.headers['Content-Length'] == '0'
@@ -318,7 +318,7 @@ class TestTestServer:
         server = Server.basic_response_server(requests_to_handle=requests_to_handle)
 
         with server as (host, port):
-            server_url = 'http://{}:{}'.format(host, port)
+            server_url = 'http://{0}:{1}'.format(host, port)
             for _ in range(requests_to_handle):
                 r = requests.get(server_url)
                 assert r.status_code == 200